Ca2+-binding protein, EF-hand superfamily [Signal transduction mechanisms];

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  10 EAELQDMINEVDADGNGTIDFPEFLTMMARKMKDTDsEEEIREAFRVFDKDGNGYISAAELRHVMTNLGekLTDEEVDEM 89
Cdd:COG5126    32 RRLWATLFSEADTDGDGRISREEFVAGMESLFEATV-EPFARAAFDLLDTDGDGKISADEFRRLLTALG--VSEEEADEL 108

                          90       100
                  ....*....|....*....|..
gi 1050115333  90 IREADIDGDGQVNYEEFVQMMT 111
Cdd:COG5126   109 FARLDTDGDGKISFEEFVAAVR 130

EF-hand domain pair;

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1050115333  47 EEEIREAFRVFDKDGNGYISAAELRHVMTNL--GEKLTDEEVDEMIREADIDGDGQVNYEEFVQMMT 111
Cdd:pfam13499   1 EEKLKEAFKLLDSDGDGYLDVEELKKLLRKLeeGEPLSDEEVEELFKEFDLDKDGRISFEEFLELYS 67

EF-hand, calcium binding motif; EF-hands are calcium-binding motifs that occur at least in pairs. Links between disease states and genes encoding EF-hands, particularly the S100 subclass, are emerging. Each motif consists of a 12 residue loop flanked on either side by a 12 residue alpha-helix. EF-hands undergo a conformational change unpon binding calcium ions.

                           10        20
                   ....*....|....*....|....*....
gi 1050115333   85 EVDEMIREADIDGDGQVNYEEFVQMMTAK 113
Cdd:smart00054   1 ELKEAFRLFDKDGDGKIDFEEFKDLLKAL 29

XopAW family type III secretion system calcium-binding effector;

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1050115333   5 GQNPTEAELQDMINEVDADGNGTIDFPEFLTMMARKMKDTDSEeeirEAFRVFDKDGNGYISAAEL 70
Cdd:NF041410   97 DQAPSTELADDLLSALDTDGDGSISSDELSAGLTSAGSSADSS----QLFSALDSDGDGSVSSDEL 158

centrin; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333   1 MRSLGQNPTEAELQDMINEVDADGNGTIDFPEFLTMMARKMKDTDSEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEK 80
Cdd:PTZ00183   43 MRSLGFEPKKEEIKQMIADVDKDGSGKIDFEEFLDIMTKKLGERDPREEILKAFRLFDDDKTGKISLKNLKRVAKELGET 122

                          90       100       110
                  ....*....|....*....|....*....|...
gi 1050115333  81 LTDEEVDEMIREADIDGDGQVNYEEFVQMMTAK 113
Cdd:PTZ00183  123 ITDEELQEMIDEADRNGDGEISEEEFYRIMKKT 155

EF-hand, calcium binding motif; A diverse superfamily of calcium sensors and calcium signal modulators; most examples in this alignment model have 2 active canonical EF hands. Ca2+ binding induces a conformational change in the EF-hand motif, leading to the activation or inactivation of target proteins. EF-hands tend to occur in pairs or higher copy numbers.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1050115333  49 EIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMIREADIDGDGQVNYEEFVQMMT 111
Cdd:cd00051     1 ELREAFRLFDKDGDGTISADELKAALKSLGEGLSEEEIDEMIREVDKDGDGKIDFEEFLELMA 63

EF-hand, calcium binding motif, found in uncharacterized calglandulin-like proteins; The family corresponds to a group of uncharacterized calglandulin-like proteins. Although their biological function remain unclear, they show high sequence similarity with human calglandulin-like protein GAGLP, which is an ortholog of calglandulin from the venom glands of Bothrops insularis snake. Both GAGLP and calglandulin are putative Ca2+-binding proteins with four EF-hand motifs. However, members in this family contain only three EF-hand motifs. In this point, they may belong to the parvalbumin-like EF-hand family, which is characterized by the presence of three consecutive EF-hand motifs (helix-loop-helix).

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  26 GTIDFPEFLTMMARKMKDTDSEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEK-----LTDEEVDEMIREADIDGDGQ 100
Cdd:cd16252    15 GSFNYSKFFEYMQKFQTSEQQEEAIRKAFQMLDKDKSGFIEWNEIKYILSTVPSSmpvapLSDEEAEAMIQAADTDGDGR 94

                          90
                  ....*....|.
gi 1050115333 101 VNYEEFVQMMT 111
Cdd:cd16252    95 IDFQEFSDMVK 105

EF-hand, calcium binding motif, found in parvalbumin-like EF-hand family; The family includes alpha- and beta-parvalbumins, and a group of uncharacterized calglandulin-like proteins. Parvalbumins are small, acidic, cytosolic EF-hand-containing Ca2+-buffer and Ca2+ transporter/shuttle proteins belonging to EF-hand superfamily. They are expressed by vertebrates in fast-twitch muscle cells, specific neurons of the central and peripheral nervous system, sensory cells of the mammalian auditory organ (Corti's cell), and some other cells, and characterized by the presence of three consecutive EF-hand motifs (helix-loop-helix) called AB, CD, and EF, but only CD and EF can chelate metal ions, such as Ca2+ and Mg2+. Thus, they may play an additional role in Mg2+ handling. Moreover, parvalbumins represent one of the major animal allergens. In metal-bound states, parvalbumins possess a rigid and stable tertiary structure and display strong allergenicity. In contrast, the metal-free parvalbumins are intrinsically disordered, and the loss of metal ions results in a conformational change that decreases their IgE binding capacity. Furthermore, parvalbumins have been widely used as a neuronal marker for a variety of functional brain systems. They also function as a Ca2+ shuttle transporting Ca2+ from troponin-C (TnC) to the sarcoplasmic reticulum (SR) Ca2+ pump during muscle relaxation. Thus they may facilitate myocardial relaxation and play important roles in cardiac diastolic dysfunction. Parvalbumins consists of alpha- and beta- sublineages, which can be distinguished on the basis of isoelectric point (pI > 5 for alpha; pI

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  26 GTIDFPEFLTMMARKMKdtdSEEEIREAFRVFDKDGNGYISAAELRHVMTNL---GEKLTDEEVDEMIREADIDGDGQVN 102
Cdd:cd16251    15 GSFNYKKFFEHVGLKQK---SEDQIKKVFQILDKDKSGFIEEEELKYILKGFsiaGRDLTDEETKALLAAGDTDGDGKIG 91

                          90
                  ....*....|
gi 1050115333 103 YEEFVQMMTA 112
Cdd:cd16251    92 VEEFATLVAG 101

Penta-EF hand, calcium binding motifs, found in Group I PEF proteins; The family corresponds to Group I PEF proteins that have been found not only in higher animals but also in lower animals, plants, fungi and protists. Group I PEF proteins include apoptosis-linked gene 2 protein (ALG-2), peflin and similar proteins. ALG-2, also termed programmed cell death protein 6 (PDCD6), is a widely expressed calcium-binding modulator protein associated with cell proliferation and death, as well as cell survival. It forms a homodimer in the cell or a heterodimer with its closest paralog peflin. Among the PEF proteins, ALG-2 can bind three Ca2+ ions through its EF1, EF3, and EF5 hands, where it is unique in that its EF5 hand binds Ca2+ ion in a canonical coordination. Peflin is a ubiquitously expressed 30-kD PEF protein containing five EF-hand motifs in its C-terminal domain and a longer N-terminal hydrophobic domain (NHB domain) than any other member of the PEF family. The NHB domain harbors nine repeats of a nonapeptide (A/PPGGPYGGP). Peflin may modulate the function of ALG-2 in Ca2+ signaling. It exists only as a heterodimer with ALG-2, and binds two Ca2+ ions through its EF1 and EF3 hands. Its additional EF5 hand is unpaired and does not bind Ca2+ ion but mediates the heterodimerization with ALG-2. The dissociation of heterodimer occurs in the presence of Ca2+.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  16 MINEVDADGNGTIDFPEFltmmarkmKDTDSE-EEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMIREAD 94
Cdd:cd16180    42 MINMFDRDRSGTINFDEF--------VGLWKYiQDWRRLFRRFDRDRSGSIDFNELQNALSSFGYRLSPQFVQLLVRKFD 113

                          90
                  ....*....|....*..
gi 1050115333  95 IDGDGQVNYEEFVQMMT 111
Cdd:cd16180   114 RRRRGSISFDDFVEACV 130

EF-hand, calcium binding motif, found in apoptosis-linked gene 2 protein (ALG-2) and similar proteins; ALG-2, also termed programmed cell death protein 6 (PDCD6), or probable calcium-binding protein ALG-2, is one of the prototypic members of the penta EF-hand protein family. It is a widely expressed calcium-binding modulator protein associated with cell proliferation and death, as well as cell survival. ALG-2 acts as a pro-apoptotic factor participating in T cell receptor-, Fas-, and glucocorticoid-induced programmed cell death, and also serves as a useful molecular marker for the prognosis of cancers. Moreover, ALG-2 functions as a calcium ion sensor at endoplasmic reticulum (ER) exit sites, and modulates ER-stress-stimulated cell death and neuronal apoptosis during organ formation. Furthermore, ALG-2 can mediate the pro-apoptotic activity of cisplatin or tumor necrosis factor alpha (TNFalpha) through the down-regulation of nuclear factor-kappaB (NF-kappaB) expression. It also inhibits angiogenesis through PI3K/mTOR/p70S6K pathway by interacting of vascular endothelial growth factor receptor-2 (VEGFR-2). In addition, nuclear ALG-2 may participate in the post-transcriptional regulation of Inositol Trisphosphate Receptor Type 1 (IP3R1) pre-mRNA at least in part by interacting with CHERP (Ca2+ homeostasis endoplasmic reticulum protein) calcium-dependently. ALG-2 contains five serially repeated EF-hand motifs and interacts with various proteins, including ALG-2-interacting protein X (Alix), Fas, annexin XI, death-associated protein kinase 1 (DAPk1), Tumor susceptibility gene 101 (TSG101), Sec31A, phospholipid scramblase 3 (PLSCR3), the P-body component PATL1, and endosomal sorting complex required for transport (ESCRT)-III-related protein IST1, in a calcium-dependent manner. It forms a homodimer in the cell or a heterodimer with its closest paralog peflin. Among the PEF proteins, ALG-2 can bind three Ca2+ ions through its EF1, EF3, and EF5 hands, where it is unique in that its EF5 hand binds Ca2+ ion in a canonical coordination.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333   7 NPTEAELqdMINEVDADGNGTIDFPEFLTMMarkmkdtDSEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEV 86
Cdd:cd16183    35 NPETVRL--MIGMFDRDNSGTINFQEFAALW-------KYITDWQNCFRSFDRDNSGNIDKNELKQALTSFGYRLSDQFY 105

                          90       100
                  ....*....|....*....|..
gi 1050115333  87 DEMIREADIDGDGQVNYEEFVQ 108
Cdd:cd16183   106 DILVRKFDRQGRGTIAFDDFIQ 127

EF-hand, calcium binding motif, found in beta-parvalbumin; Beta-parvalbumin, also termed Oncomodulin-1 (OM), is a small calcium-binding protein that is expressed in hepatomas, as well as in the blastocyst and the cytotrophoblasts of the placenta. It is also found to be expressed in the cochlear outer hair cells of the organ of Corti and frequently expressed in neoplasms. Mammalian beta-parvalbumin is secreted by activated macrophages and neutrophils. It may function as a tissue-specific Ca2+-dependent regulatory protein, and may also serve as a specialized cytosolic Ca2+ buffer. Beta-parvalbumin acts as a potent growth-promoting signal between the innate immune system and neurons in vivo. It has high and specific affinity for its receptor on retinal ganglion cells (RGC) and functions as the principal mediator of optic nerve regeneration. It exerts its effects in a cyclic adenosine monophosphate (cAMP)-dependent manner and can further elevate intracellular cAMP levels. Moreover, beta-parvalbumin is associated with efferent function and outer hair cell electromotility, and can identify different hair cell types in the mammalian inner ear. Beta-parvalbumin is characterized by the presence of three consecutive EF-hand motifs (helix-loop-helix) called AB, CD, and EF, but only CD and EF can chelate metal ions, such as Ca2+ and Mg2+. The EF site displays a high-affinity for Ca2+/Mg2+, and the CD site is a low-affinity Ca2+-specific site. In addition, beta-parvalbumin is distinguished from other parvalbumins by its unusually low isoelectric point (pI = 3.1) and sequence eccentricities (e.g., Y57-L58-D59 instead of F57-I58-E59).

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  46 SEEEIREAFRVFDKDGNGYISAAELRHVMTNL---GEKLTDEEVDEMIREADIDGDGQVNYEEFVQMMTA 112
Cdd:cd16255    32 SADDVKKVFEIIDQDKSGFIEEEELKLFLQNFssgARELTDAETKAFLKAGDSDGDGKIGVEEFQALVKA 101

Penta-EF hand, calcium binding motifs, found in PEF calpain family; The PEF calpain family belongs to the second group of penta-EF hand (PEF) proteins. It includes classical (also called conventional or typical) calpain (referring to a calcium-dependent papain-like enzymes, EC 3.4.22.17) large catalytic subunits (CAPN1, 2, 3, 8, 9, 11, 12, 13, 14) and two calpain small subunits (CAPNS1 and CAPNS2), which are largely confined to animals (metazoans). These PEF-containing are nonlysosomal intracellular calcium-activated intracellular cysteine proteases that play important roles in the degradation or functional modulation in a variety of substrates in response to calcium signalling. The classical mu- and m-calpains are heterodimers consisting of homologous but a distinct (large) L-subunit/chain (CAPN1 or CAPN2) and a common (small) S-subunit/chain (CAPNS1 or CAPNS2). These L-subunits (CAPN1 and CAPN2) and S-subunit CAPNS1 are ubiquitously found in all tissues. Other calpains likely consist of an isolated L-subunit/chain alone. Many of them, such as CAPNS2, CAPN3 (in skeletal muscle, or lens), CAPN8 (in stomach), CAPN9 (in digestive tracts), CAPN11 (in testis), CAPN12 (in follicles), are tissue-specific and have specific functions in distinct organs. The L-subunits of similar structure (called CALPA and B) also have been found in Drosophila melanogaster. The S-subunit seems to have a chaperone-like function for proper folding of the L-subunit. The catalytic L-subunits contain a short N-terminal anchor helix, followed by a calpain cysteine protease (CysPc) domain, a C2-domain-like (C2L) domain, and a C-terminal Ca2+-binding penta-EF-hand (PEF) domain. The S-subunits only have the PEF domain following an N-terminal Gly-rich hydrophobic domain. The calpains undergo a rearrangement of the protein backbone upon Ca2+-binding.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  16 MINEVDADGNGTIDFPEFLTMMARKmkdtdseEEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLtDEEVDEMIREADI 95
Cdd:cd16182    47 LIALMDTNGSGRLDLEEFKTLWSDL-------KKWQAIFKKFDTDRSGTLSSYELRKALESAGFHL-SNKVLQALVLRYA 118

                          90
                  ....*....|...
gi 1050115333  96 DGDGQVNYEEFVQ 108
Cdd:cd16182   119 DSTGRITFEDFVS 131

XopAW family type III secretion system calcium-binding effector;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333   3 SLGQNPTEAELQ-DMINEVDADGNGTIDFPEFLTMMARKmKDTDSEEEIREAFRVFDKDGNGYISAAELRHVMTN----L 77
Cdd:NF041410   18 SSTSSARSQQFQkQLFAKLDSDGDGSVSQDELSSALSSK-SDDGSLIDLSELFSDLDSDGDGSLSSDELAAAAPPppppP 96

                          90       100
                  ....*....|....*....|....*....
gi 1050115333  78 GEKLTDEEVDEMIREADIDGDGQVNYEEF 106
Cdd:NF041410   97 DQAPSTELADDLLSALDTDGDGSISSDEL 125

EF-hand, calcium binding motif, found in alpha-parvalbumin; Alpha-parvalbumin is cytosolic Ca2+/Mg2+-binding protein expressed mainly in fast-twitch skeletal myofibrils, where it may act as a soluble relaxing factor facilitating the Ca2+-mediated relaxation phase. It is also expressed in rapidly firing neurons, particularly GABA-ergic neurons, and thus may confer protection against Ca2+ toxicity. The major role of alpha-parvalbumin is metal buffering and transport of Ca2+. It binds different metal cations, and exhibits very high affinity for Ca2+ and physiologically significant affinity for Mg2+. Alpha-parvalbumin is characterized by the presence of three consecutive EF-hand motifs (helix-loop-helix) called AB, CD, and EF, but only CD and EF can chelate metal ions, such as Ca2+ and Mg2+. Both metal ion-binding sites in alpha-parvalbumin are high-affinity sites. Additionally, in contrast to beta-parvalbumin, alpha-parvalbumin is less acidic and has an additional residue in the C-terminal helix.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  26 GTIDFPEFLTMMARKMKdtdSEEEIREAFRVFDKDGNGYISAAELRHVMTNL---GEKLTDEEVDEMIREADIDGDGQVN 102
Cdd:cd16254    15 DSFDYKKFFEMVGLKKK---SADDVKKVFHILDKDKSGFIEEDELKFVLKGFspdGRDLSDKETKALLAAGDKDGDGKIG 91

                  ....*...
gi 1050115333 103 YEEFVQMM 110
Cdd:cd16254    92 IDEFATLV 99

EF-hand motif found in eukaryotic phosphoinositide-specific phospholipase C (PI-PLC, EC 3.1.4.11) isozymes; PI-PLC isozymes are signaling enzymes that hydrolyze the membrane phospholipids phosphatidylinositol-4,5-bisphosphate (PIP2) to generate two important second messengers in eukaryotic signal transduction cascades, Inositol 1,4,5-trisphosphate (InsP3) and diacylglycerol (DAG). InsP3 triggers inflow of calcium from intracellular stores, while DAG, together with calcium, activates protein kinase C, which goes on to phosphorylate other molecules, leading to altered cellular activity. Calcium is required for the catalysis. This family corresponds to the four EF-hand motifs containing PI-PLC isozymes, including PI-PLC-beta (1-4), -gamma (1-2), -delta (1,3,4), -epsilon (1), -zeta (1), eta (1-2). Lower eukaryotes such as yeast and slime molds contain only delta-type isozymes. In contrast, other types of isoforms present in higher eukaryotes. This family also includes 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase 1 (PLC1) from fungi. Some homologs from plants contain only two atypical EF-hand motifs and they are not included. All PI-PLC isozymes except sperm-specific PI-PLC-zeta share a core set of domains, including an N-terminal pleckstrin homology (PH) domain, four atypical EF-hand motifs, a PLC catalytic core, and a single C2 domain. PI-PLC-zeta lacks the PH domain. The PLC catalytic core domain is a TIM barrel with two highly conserved regions (X and Y) split by a highly degenerate linker sequence. Most of EF-hand motifs found in PI-PLCs consist of a helix-loop-helix structure, but lack residues critical to metal binding. Moreover, the EF-hand region of most of PI-PLCs may have an important regulatory function, but it has yet to be identified. However, PI-PLC-zeta is a key exception. It is responsible for Ca2+ oscillations in fertilized oocytes and exhibits a high sensitivity to Ca2+ mediated through its EF-hand domain. In addition, PI-PLC-eta2 shows a canonical EF-loop directing Ca2+-sensitivity and thus can amplify transient Ca2+ signals. Also it appears that PI-PLC-delta1 can regulate the binding of PH domain to PIP2 in a Ca2+-dependent manner through its functionally important EF-hand domains. PI-PLCs can be activated by a variety of extracellular ligands, such as growth factors, hormones, cytokines and lipids. Their activation has been implicated in tumorigenesis and/or metastasis linked to migration, proliferation, growth, inflammation, angiogenesis and actin cytoskeleton reorganization. PI-PLC-beta isozymes are activated by G-protein coupled receptor (GPCR) through different mechanisms. However, PI-PLC-gamma isozymes are activated by receptor tyrosine kinase (RTK), such as Rho and Ras GTPases. In contrast, PI-PLC-epsilon are activated by both GPCR and RTK. PI-PLC-delta1 and PLC-eta 1 are activated by GPCR-mediated calcium mobilization. The activation mechanism for PI-PLC-zeta remains unclear.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333   1 MRSLGQNPTEAELQDMINEVDADGNGTIDFPEFLTMMARKMkdtdSEEEIREAFRVFDKDGNGYISAAELRHVMTN-LGE 79
Cdd:cd15898    26 LKRLNIRVSEKELKKLFKEVDTNGDGTLTFDEFEELYKSLT----ERPELEPIFKKYAGTNRDYMTLEEFIRFLREeQGE 101

                          90       100       110
                  ....*....|....*....|....*....|..
gi 1050115333  80 KLTDEEVDEMIREADIDG-DGQVNYEEFVQMM 110
Cdd:cd15898   102 NVSEEECEELIEKYEPEReNRQLSFEGFTNFL 133

EF-hand, calcium binding motif, found in the hexa-EF hand proteins family; The hexa-EF hand proteins family, also named the calbindin sub-family, contains a group of six EF-hand Ca2+-binding proteins, including calretinin (CR, also termed 29 kDa calbindin), calbindin D28K (CB, also termed vitamin D-dependent calcium-binding protein, avian-type), and secretagogin (SCGN). CR is a cytosolic hexa-EF-hand calcium-binding protein predominantly expressed in a variety of normal and tumorigenic t-specific neurons of the central and peripheral nervous system. It is a multifunctional protein implicated in many biological processes, including cell proliferation, differentiation, and cell death. CB is highly expressed in brain tissue. It is a strong calcium-binding and buffering protein responsible for preventing a neuronal death as well as maintaining and controlling calcium homeostasis. SCGN is a six EF-hand calcium-binding protein expressed in neuroendocrine, pancreatic endocrine and retinal cells. It plays a crucial role in cell apoptosis, receptor signaling and differentiation. It is also involved in vesicle secretion through binding to various proteins, including interacts with SNAP25, SNAP23, DOC2alpha, ARFGAP2, rootletin, KIF5B, beta-tubulin, DDAH-2, ATP-synthase and myeloid leukemia factor 2. SCGN functions as a Ca2+ sensor/coincidence detector modulating vesicular exocytosis of neurotransmitters, neuropeptides or hormones. Although the family members share a significant amount of secondary sequence homology, they display altered structural and biochemical characteristics, and operate in distinct fashions. CB contains six EF-hand motifs in a single globular domain, where EF-hands 1, 3, 4, 5 bind four calcium ions. CR contains six EF-hand motifs within two independent domains, CR I-II and CR III-VI. They harbor two and four EF-hand motifs, respectively. The first 5 EF-hand motifs are capable of binding calcium ions, while the EF-hand 6 is inactive. SCGN consists of the three globular domains each of which contains a pair of EF-hand motifs. Human SCGN simultaneously binds four calcium ions through its EF-hands 3, 4, 5 and 6 in one high affinity and three low affinity calcium-binding sites. In contrast, SCGNs in other lower eukaryotes, such as D. rerio, X. laevis, M. domestica, G. gallus, O. anatinus, are fully competent in terms of six calcium-binding.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333   3 SLGQNPTEAELQDMINEV----DADGNGTIDFPEFLTMMA---------RKMKDTDSEEEIREAFRVFDKDGNGYISAAE 69
Cdd:cd15902    32 LNGKDKTDDEVAEKKKEFmekyDENEDGKIEIRELANILPteenflllfRREQPLISSVEFMKIWRKYDTDGSGFIEAKE 111

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*....
gi 1050115333  70 LRHVMTNLGEKL--------TDEEVDEMIREADIDGDGQVNYEEFVQMM 110
Cdd:cd15902   112 LKGFLKDLLLKNkkhvsppkLDEYTKLILKEFDANKDGKLELDEMAKLL 160

N-terminal domain of Myosin essential light chain ELC; ELC is part of the apicomplexan membrane-associated protein complex called the glideosome, which is essential for parasite motility. The glideosome is composed of six proteins: myosin A (MyoA), essential light chain ELC, myosin light chain MLC1 (also called MTIP), and the glideosome-associated proteins GAP40, GAP45, and GAP50. MyoA is a Class XIV myosin implicated in gliding motility, as well as host cell and tissue invasion by parasites. ELC binds to the MyoA neck region adjacent to the MLC1-binding site, and both myosin light chains co-located to the glideosome. Although ELCs bind to a conserved MyoA sequence, P. falciparum ELC adopts a distinct structure in the free and MyoA-bound state. Therefore ELCs enhance MyoA performance by inducing alpha helical structure formation in MyoA and thus stiffening its lever arm. It has been shown that disruption of MyoA, MLC1, or ELC have dramatic effects on parasite motility but do not affect parasite shape or replication. The ELC N-terminal domain is part of the EF-hand calcium binding motif superfamily. Calcium binding has no effect on the structure of ELCs.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 1050115333  46 SEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMireadidgDGQVNYEEFVQMMTAK 113
Cdd:cd22949     1 MEEKFREAFILFDRDGDGELTMYEAVLAMRSCGIPLTNDEKDAL--------PASMNWDQFENWAKKK 60

Penta-EF hand, calcium binding motifs, found in sorcin, grancalcin, and similar proteins; The family corresponds to the second group of penta-EF hand (PEF) proteins that includes sorcin, grancalcin, and similar proteins. Sorcin, also termed 22 kDa Ca2+-binding protein, CP-22, or V19, is a soluble resistance-related calcium-binding protein that is expressed in normal mammalian tissues, such as the liver, lungs and heart. It contains a flexible glycine and proline-rich N-terminal extension and five EF-hand motifs that associate with membranes in a calcium-dependent manner. It may harbor three potential Ca2+ binding sites through its EF1, EF2 and EF3 hands. However, binding of only two Ca2+/monomer suffices to trigger the conformational change that exposes hydrophobic regions and leads to interaction with the respective targets. Sorcin forms homodimers through the association of the unpaired EF5 hand. Among the PEF proteins, sorcin is unique in that it contains potential phosphorylation sites by cAMP-dependent protein kinase (PKA), and it can form a tetramer at slightly acid pH values although remaining a stable dimer at neutral pH. Grancalcin (GCA) is a cytosolic Ca2+-binding protein specifically expressed in neutrophils and monocytes/macrophages. It can strongly interact with sorcin to form a heterodimer and further modulate the function of sorcin. GCA exists as homodimers in solution. It contains five EF-hand motifs attached to an N-terminal region of an approximately 50 residue-long segment rich in glycines and prolines. In contrast with sorcin, GCA binds two Ca2+ ions through its EF1 and EF3 hands.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  16 MINEVDADGNGTIDFPEFLTMMArkmkdtdSEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMIREADI 95
Cdd:cd16181    45 MIAMLDRDHSGKMGFNEFKELWA-------ALNQWKTTFMQYDRDRSGTVEPQELQQAIRSFGYNLSPQALNVIVKRYSK 117

                          90
                  ....*....|..
gi 1050115333  96 dgDGQVNYEEFV 107
Cdd:cd16181   118 --NGRITFDDFV 127

Eps15 homology domain; found in proteins implicated in endocytosis, vesicle transport, and signal transduction. The alignment contains a pair of EF-hand motifs, typically one of them is canonical and binds to Ca2+, while the other may not bind to Ca2+. A hydrophobic binding pocket is formed by residues from both EF-hand motifs. The EH domain binds to proteins containing NPF (class I), [WF]W or SWG (class II), or H[TS]F (class III) sequence motifs.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*.
gi 1050115333  52 EAFRVFDKDGNGYISAAELRHVMTNLGekLTDEEVDEMIREADIDGDGQVNYEEFV 107
Cdd:cd00052     3 QIFRSLDPDGDGLISGDEARPFLGKSG--LPRSVLAQIWDLADTDKDGKLDKEEFA 56

EF-hand motif found in phosphoinositide phospholipase C delta (PI-PLC-delta); PI-PLC-delta isozymes represent a class of metazoan PI-PLCs that are some of the most sensitive to calcium among all PLCs. Their activation is modulated by intracellular calcium ion concentration, phospholipids, polyamines, and other proteins, such as RhoAGAP. Like other PI-PLC isozymes, PI-PLC-delta isozymes contain a core set of domains, including an N-terminal pleckstrin homology (PH) domain, four atypical EF-hand motifs, a PLC catalytic core, and a single C-terminal C2 domain. The PLC catalytic core domain is a TIM barrel with two highly conserved regions (X and Y) split by a highly degenerate linker sequence. There are three PI-PLC-delta isozymes (1, 3 and 4). PI-PLC-delta1 is relatively well characterized. It is activated by high calcium levels generated by other PI-PLC family members, and therefore functions as a calcium amplifier within the cell. Different PI-PLC-delta isozymes have different tissue distribution and different subcellular locations. PI-PLC-delta1 is mostly a cytoplasmic protein, PI-PLC-delta3 is located in the membrane, and PI-PLC-delta4 is predominantly detected in the cell nucleus. PI-PLC-delta isozymes is evolutionarily conserved even in non-mammalian species, such as yeast, slime molds and plants.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 1050115333  50 IREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMIREADIDGDGQVNYEEFVQ 108
Cdd:cd16202     2 LKDQFRKADKNGDGKLSFKECKKLLKKLNVKVDKDYAKKLFQEADTSGEDVLDEEEFVQ 60

The penta-EF hand (PEF) family; The penta-EF hand (PEF) family contains a group of five EF-hand calcium-binding proteins, including several classical calpain large catalytic subunits (CAPN1, 2, 3, 8, 9, 11, 12, 13, 14), two calpain small subunits (CAPNS1 and CAPNS2), as well as non-calpain PEF proteins, ALG-2 (apoptosis-linked gene 2, also termed programmed cell death protein 6, PDCD6), peflin, sorcin, and grancalcin. Based on the sequence similarity of EF1 hand, ALG-2 and peflin have been classified into group I PEF proteins. Calcium-dependent protease calpain subfamily members, sorcin and grancalcin, are group II PEF proteins. Calpains (EC 3.4.22.17) are calcium-activated intracellular cysteine proteases that play important roles in the degradation or functional modulation in a variety of substrates. They have been implicated in a number of physiological processes such as cell cycle progression, remodeling of cytoskeletal-cell membrane attachments, signal transduction, gene expression and apoptosis. ALG-2 is a pro-apoptotic factor that forms a homodimer in the cell or a heterodimer with its closest paralog peflin through their EF5s. Peflin is a 30-kD PEF protein with a longer N-terminal hydrophobic domain than any other member of the PEF family, and it contains nine nonapeptide (A/PPGGPYGGP) repeats. It exists only as a heterodimer with ALG-2. The dissociation of heterodimer occurs in the presence of Ca2+. ALG-2 interacts with various proteins in a Ca2+-dependent manner. Sorcin (for soluble resistance-related calcium binding protein) is a soluble resistance-related calcium-binding protein that participates in the regulation of calcium homeostasis in cells. Grancalcin is a cytosolic Ca2+-binding protein specifically expressed in neutrophils and monocytes/macrophages. It plays a key role in leukocyte-specific functions that are responsible for host defense. Grancalcin can form a heterodimer together with sorcin. Members in this family contain five EF-hand motifs attached to an N-terminal region of variable length containing one or more short Gly/Pro-rich sequences. These proteins form homodimers or heterodimers through pairing between the 5th EF-hands from the two molecules. Unlike calmodulin, the PEF domains do not undergo major conformational changes upon binding Ca2+.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  16 MINEVDADGNGTIDFPEFlTMMARKMKDtdseeeIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMIREADi 95
Cdd:cd15897    45 MIAMMDRDHSGKLNFSEF-KGLWNYIKA------WQEIFRTYDTDGSGTIDSNELRQALSGAGYRLSEQTYDIIIRRYD- 116

                          90
                  ....*....|...
gi 1050115333  96 DGDGQVNYEEFVQ 108
Cdd:cd15897   117 RGRGNIDFDDFIQ 129

EF-hand, calcium binding motif, found in peflin and similar proteins; Peflin, also termed penta-EF hand (PEF) protein with a long N-terminal hydrophobic domain, or penta-EF hand domain-containing protein 1, is a ubiquitously expressed 30-kD PEF protein containing five EF-hand motifs in its C-terminal domain and a longer N-terminal hydrophobic domain (NHB domain) than any other member of the PEF family. The NHB domain harbors nine repeats of a nonapeptide (A/PPGGPYGGP). Peflin may modulate the function of ALG-2 in Ca2+ signaling. It exists only as a heterodimer with ALG-2, and binds two Ca2+ ions through its EF1 and EF3 hands. Its additional EF5 hand is unpaired and does not bind Ca2+ ion but mediates the heterodimerization with ALG-2. The dissociation of heterodimer occurs in the presence of Ca2+. In lower vertebrates, peflin may interact with transient receptor potential N (TRPN1), suggesting a potential role of peflin in fast transducer channel adaptation.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  16 MINEVDADGNGTIDFPEFltmmarkmkdtdSE-----EEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMI 90
Cdd:cd16184    42 MIGMFDKDKSGTIDIYEF------------QAlwnyiQQWKQVFQQFDRDRSGSIDENELHQALSQMGYRLSPQFVQFLV 109

                          90
                  ....*....|....*...
gi 1050115333  91 READIDGDGQVNYEEFVQ 108
Cdd:cd16184   110 SKYDPRARRSLTLDQFIQ 127

XopAW family type III secretion system calcium-binding effector;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  21 DADGNGTIDFPEFLTMMA------RKMKDTDSEEEIreaFRVFDKDGNGYISAAELRHVMTNLGeklTDEEVDEMIREAD 94
Cdd:NF041410   73 DSDGDGSLSSDELAAAAPppppppDQAPSTELADDL---LSALDTDGDGSISSDELSAGLTSAG---SSADSSQLFSALD 146

                          90
                  ....*....|..
gi 1050115333  95 IDGDGQVNYEEF 106
Cdd:NF041410  147 SDGDGSVSSDEL 158

EF-hand, calcium binding motif; EF-hands are calcium-binding motifs that occur at least in pairs. Links between disease states and genes encoding EF-hands, particularly the S100 subclass, are emerging. Each motif consists of a 12 residue loop flanked on either side by a 12 residue alpha-helix. EF-hands undergo a conformational change unpon binding calcium ions.

                           10        20
                   ....*....|....*....|....*....
gi 1050115333   49 EIREAFRVFDKDGNGYISAAELRHVMTNL 77
Cdd:smart00054   1 ELKEAFRLFDKDGDGKIDFEEFKDLLKAL 29

Ca2+-binding protein, EF-hand superfamily [Signal transduction mechanisms];

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1050115333  47 EEEIREAFRVFDKDGNGYISAAELrhvmtnlgEKLTDEEVDEMIREADIDGDGQVNYEEFVQMMTA 112
Cdd:COG5126     4 RRKLDRRFDLLDADGDGVLERDDF--------EALFRRLWATLFSEADTDGDGRISREEFVAGMES 61

EF hand; The EF-hands can be divided into two classes: signalling proteins and buffering/transport proteins. The first group is the largest and includes the most well-known members of the family such as calmodulin, troponin C and S100B. These proteins typically undergo a calcium-dependent conformational change which opens a target binding site. The latter group is represented by calbindin D9k and do not undergo calcium dependent conformational changes.

                          10        20
                  ....*....|....*....|....*....
gi 1050115333  49 EIREAFRVFDKDGNGYISAAELRHVMTNL 77
Cdd:pfam00036   1 ELKEIFRLFDKDGDGKIDFEEFKELLKKL 29

Penta-EF hand, calcium binding motifs, found in Drosophila melanogaster calpain-A (CalpA), calpain-B (CalpB), and similar proteins; The family contains two calpains that have been found in Drosophila, CalpA and CalpB. CalpA, also termed calcium-activated neutral proteinase A (CANP A), or calpain-A catalytic subunit, is a Drosophila calpain homolog specifically expressed in a few neurons in the central nervous system, in scattered endocrine cells in the midgut, and in blood cells. CalpB, also termed calcium-activated neutral proteinase B (CANP B), contains calpain-B catalytic subunit 1 and calpain-B catalytic subunit 2. Both CalpA and CalpB are closely related to that of vertebrate calpains, and they share similar domain architecture, which consists of four domains: the N-terminal domain I, the catalytic domain II carrying the three active site residues, Cys, His and Asn, the Ca2+-regulated phospholipid-binding domain III, and penta-EF-hand Ca2+-binding domain IV. Besides, CalpA and CalpB display some distinguishing structural features that are not found in mammalian typical calpains. CalpA harbors a 76 amino acid long hydrophobic stretch inserted in domain IV, which may be involved in membrane attachment of this enzyme. CalpB has an unusually long N-terminal tail of 224 amino acids, which belongs to the class of intrinsically unstructured proteins (IUP) and may become ordered upon binding to target protein(s). Moreover, they do not need small regulatory subunits for their catalytic activity, and their proteolytic function is not regulated by an intrinsic inhibitor as the Drosophila genome contains neither regulatory subunit nor calpastatin orthologs. As a result, they may exist as a monomer or perhaps as a homo- or heterodimer together with a second large subunit. Furthermore, both CalpA and CalpB are dispensable for viability and fertility and do not share vital functions during Drosophila development. Phosphatidylinositol 4,5-diphosphate, phosphatidylinositol 4-monophosphate, phosphatidylinositol, and phosphatidic acid can stimulate the activity and the rate of activation of CalpA, but not CalpB. Calpain A modulates Toll responses by limited Cactus/IkappaB proteolysis. CalpB directly interacts with talin, an important component of the focal adhesion complex, and functions as an important modulator in border cell migration within egg chambers, which may act via the digestion of talin. CalpB can be phosphorylated by cAMP-dependent protein kinase (protein kinase A, PKA; EC 2.7.11.11) at Ser240 and Ser845, as well as by mitogen-activated protein kinase (ERK1 and ERK2; EC 2.7.11.24) at Thr747. The activation of the ERK pathway by extracellular signals results in the phosphorylation and activation of calpain B. In Schneider cells (S2), calpain B was mainly in the cytoplasm and upon a rise in Ca2+ the enzyme adhered to intracellular membranes.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  16 MINEVDADGNGTIDFPEF--LTMMARKMKDtdseeeireAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMI-RE 92
Cdd:cd16196    46 MVAMMDVDRSGKLGFEEFkkLWEDLRSWKR---------VFKLFDTDGSGSFSSFELRNALNSAGFRLSNATLNALVlRY 116

                          90
                  ....*....|....*....
gi 1050115333  93 AdiDGDGQVNYEEFVQMMT 111
Cdd:cd16196   117 S--NKDGRISFDDFIMCAV 133

EF-hand, calcium binding motif, found in calumenin, reticulocalbin-1 (RCN-1), reticulocalbin-3 (RCN-3), and similar proteins; The family corresponds to a group of six EF-hand Ca2+-binding proteins, including calumenin (also known as crocalbin or CBP-50), reticulocalbin-1 (RCN-1), reticulocalbin-3 (RCN-3), and similar proteins. Calumenin is an endo/sarcoplasmic reticulum (ER/SR) resident low-affinity Ca2+-binding protein that contains six EF-hand domains and a C-terminal SR retention signal His-Asp-Glu-Phe (HDEF) tetrapeptide. It functions as a novel regulator of SERCA2, and its expressional changes are tightly coupled with Ca2+-cycling of cardiomyocytes. It is also broadly involved in haemostasis and in the pathophysiology of thrombosis. Moreover, the extracellular calumenin acts as a suppressor of cell migration and tumor metastasis. RCN-1 is an endoplasmic reticulum resident Ca2+-binding protein with a carboxyl-terminal His-Asp-Glu-Leu (HDEL) tetrapeptide signal. It acts as a potential negative regulator of B-RAF activation and can negatively modulate cardiomyocyte hypertrophy by inhibition of the mitogen-activated protein kinase signalling cascade. It also plays a key role in the development of doxorubicin-associated resistance. RCN-3 is a putative six EF-hand Ca2+-binding protein that contains five RXXR (X is any amino acid) motifs and a C-terminal ER retrieval signal HDEL tetrapeptide. The RXXR motif represents the target sequence of subtilisin-like proprotein convertases (SPCs). RCN-3 is specifically bound to the paired basic amino-acid-cleaving enzyme-4 (PACE4) precursor protein and plays an important role in the biosynthesis of PACE4.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  13 LQDMINEVDADGNGTIDFPEfLTMMARKMKDTDSEEEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVD----- 87
Cdd:cd16226    37 LGIIVDKIDKNGDGFVTEEE-LKDWIKYVQKKYIREDVDRQWKEYDPNKDGKLSWEEYKKATYGFLDDEEEDDDLhesyk 115

                          90       100
                  ....*....|....*....|....*.
gi 1050115333  88 EMIR-------EADIDGDGQVNYEEF 106
Cdd:cd16226   116 KMIRrderrwkAADQDGDGKLTKEEF 141

EF-hand motif found in eukaryotic phosphoinositide-specific phospholipase C (PI-PLC, EC 3.1.4.11) isozymes; PI-PLC isozymes are signaling enzymes that hydrolyze the membrane phospholipids phosphatidylinositol-4,5-bisphosphate (PIP2) to generate two important second messengers in eukaryotic signal transduction cascades, Inositol 1,4,5-trisphosphate (InsP3) and diacylglycerol (DAG). InsP3 triggers inflow of calcium from intracellular stores, while DAG, together with calcium, activates protein kinase C, which goes on to phosphorylate other molecules, leading to altered cellular activity. Calcium is required for the catalysis. This family corresponds to the four EF-hand motifs containing PI-PLC isozymes, including PI-PLC-beta (1-4), -gamma (1-2), -delta (1,3,4), -epsilon (1), -zeta (1), eta (1-2). Lower eukaryotes such as yeast and slime molds contain only delta-type isozymes. In contrast, other types of isoforms present in higher eukaryotes. This family also includes 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase 1 (PLC1) from fungi. Some homologs from plants contain only two atypical EF-hand motifs and they are not included. All PI-PLC isozymes except sperm-specific PI-PLC-zeta share a core set of domains, including an N-terminal pleckstrin homology (PH) domain, four atypical EF-hand motifs, a PLC catalytic core, and a single C2 domain. PI-PLC-zeta lacks the PH domain. The PLC catalytic core domain is a TIM barrel with two highly conserved regions (X and Y) split by a highly degenerate linker sequence. Most of EF-hand motifs found in PI-PLCs consist of a helix-loop-helix structure, but lack residues critical to metal binding. Moreover, the EF-hand region of most of PI-PLCs may have an important regulatory function, but it has yet to be identified. However, PI-PLC-zeta is a key exception. It is responsible for Ca2+ oscillations in fertilized oocytes and exhibits a high sensitivity to Ca2+ mediated through its EF-hand domain. In addition, PI-PLC-eta2 shows a canonical EF-loop directing Ca2+-sensitivity and thus can amplify transient Ca2+ signals. Also it appears that PI-PLC-delta1 can regulate the binding of PH domain to PIP2 in a Ca2+-dependent manner through its functionally important EF-hand domains. PI-PLCs can be activated by a variety of extracellular ligands, such as growth factors, hormones, cytokines and lipids. Their activation has been implicated in tumorigenesis and/or metastasis linked to migration, proliferation, growth, inflammation, angiogenesis and actin cytoskeleton reorganization. PI-PLC-beta isozymes are activated by G-protein coupled receptor (GPCR) through different mechanisms. However, PI-PLC-gamma isozymes are activated by receptor tyrosine kinase (RTK), such as Rho and Ras GTPases. In contrast, PI-PLC-epsilon are activated by both GPCR and RTK. PI-PLC-delta1 and PLC-eta 1 are activated by GPCR-mediated calcium mobilization. The activation mechanism for PI-PLC-zeta remains unclear.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 1050115333  50 IREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMIREADIDGDGQVNYEEFVQMM 110
Cdd:cd15898     2 LRRQWIKADKDGDGKLSLKEIKKLLKRLNIRVSEKELKKLFKEVDTNGDGTLTFDEFEELY 62

XopAW family type III secretion system calcium-binding effector;

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1050115333   5 GQNPTEAELQDMINEVDADGNGTIDFPEFLTMMARKMKDTDSEeeirEAFRVFDKDGNGYISAAEL 70
Cdd:NF041410   97 DQAPSTELADDLLSALDTDGDGSISSDELSAGLTSAGSSADSS----QLFSALDSDGDGSVSSDEL 158

EF-hand, calcium binding motif, found in mitochondrial calcium uptake proteins MICU1, MICU2, MICU3, and similar proteins; This family includes mitochondrial calcium uptake protein MICU1 and its two additional paralogs, MICU2 and MICU3. MICU1 localizes to the inner mitochondrial membrane (IMM). It functions as a gatekeeper of the mitochondrial calcium uniporter (MCU) and regulates MCU-mediated mitochondrial Ca2+ uptake, which is essential for maintaining mitochondrial homoeostasis. MICU1 and MICU2 are physically associated within the uniporter complex and are co-expressed across all tissues. They may play non-redundant roles in the regulation of the mitochondrial calcium uniporter. At present, the precise molecular function of MICU2 and MICU3 remain unclear. MICU2 may play possible roles in Ca2+ sensing and regulation of MCU, calcium buffering with a secondary impact on transport or assembly and stabilization of MCU. MICU3 likely has a role in mitochondrial calcium handling. All members in this family contains an N-terminal mitochondrial targeting sequence (MTS) as well as two evolutionarily conserved canonical Ca2+-binding EF-hands separated by a long stretch of residues predicted to form alpha-helices.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333  23 DGNGTIDFPEFLTMMARKMKDTDseeEIREAFRvFDKDGNGYISAAELRHVM-TNLGEKLTDEEVDEMIREADIDGDGQV 101
Cdd:cd15900    64 DGKQKLSIEKFLEFQENLQEEID---DVDTALT-FYHLAGASIDRKTFKRAAkVVAGVELSDHVVDVVFTIFDEDGDGIL 139

                  ....*....
gi 1050115333 102 NYEEFVQMM 110
Cdd:cd15900   140 SHKEFISVM 148

EF-hand, calcium binding motif, found in apoptosis-linked gene 2 protein (ALG-2) and similar proteins; ALG-2, also termed programmed cell death protein 6 (PDCD6), or probable calcium-binding protein ALG-2, is one of the prototypic members of the penta EF-hand protein family. It is a widely expressed calcium-binding modulator protein associated with cell proliferation and death, as well as cell survival. ALG-2 acts as a pro-apoptotic factor participating in T cell receptor-, Fas-, and glucocorticoid-induced programmed cell death, and also serves as a useful molecular marker for the prognosis of cancers. Moreover, ALG-2 functions as a calcium ion sensor at endoplasmic reticulum (ER) exit sites, and modulates ER-stress-stimulated cell death and neuronal apoptosis during organ formation. Furthermore, ALG-2 can mediate the pro-apoptotic activity of cisplatin or tumor necrosis factor alpha (TNFalpha) through the down-regulation of nuclear factor-kappaB (NF-kappaB) expression. It also inhibits angiogenesis through PI3K/mTOR/p70S6K pathway by interacting of vascular endothelial growth factor receptor-2 (VEGFR-2). In addition, nuclear ALG-2 may participate in the post-transcriptional regulation of Inositol Trisphosphate Receptor Type 1 (IP3R1) pre-mRNA at least in part by interacting with CHERP (Ca2+ homeostasis endoplasmic reticulum protein) calcium-dependently. ALG-2 contains five serially repeated EF-hand motifs and interacts with various proteins, including ALG-2-interacting protein X (Alix), Fas, annexin XI, death-associated protein kinase 1 (DAPk1), Tumor susceptibility gene 101 (TSG101), Sec31A, phospholipid scramblase 3 (PLSCR3), the P-body component PATL1, and endosomal sorting complex required for transport (ESCRT)-III-related protein IST1, in a calcium-dependent manner. It forms a homodimer in the cell or a heterodimer with its closest paralog peflin. Among the PEF proteins, ALG-2 can bind three Ca2+ ions through its EF1, EF3, and EF5 hands, where it is unique in that its EF5 hand binds Ca2+ ion in a canonical coordination.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 1050115333  54 FRVFDKDGNGYISAAELRHVMTNlG--EKLTDEEVDEMIREADIDGDGQVNYEEF 106
Cdd:cd16183     6 FQRVDKDRSGQISATELQQALSN-GtwTPFNPETVRLMIGMFDRDNSGTINFQEF 59

S-100: S-100 domain, which represents the largest family within the superfamily of proteins carrying the Ca-binding EF-hand motif. Note that this S-100 hierarchy contains only S-100 EF-hand domains, other EF-hands have been modeled separately. S100 proteins are expressed exclusively in vertebrates, and are implicated in intracellular and extracellular regulatory activities. Intracellularly, S100 proteins act as Ca-signaling or Ca-buffering proteins. The most unusual characteristic of certain S100 proteins is their occurrence in extracellular space, where they act in a cytokine-like manner through RAGE, the receptor for advanced glycation products. Structural data suggest that many S100 members exist within cells as homo- or heterodimers and even oligomers; oligomerization contributes to their functional diversification. Upon binding calcium, most S100 proteins change conformation to a more open structure exposing a hydrophobic cleft. This hydrophobic surface represents the interaction site of S100 proteins with their target proteins. There is experimental evidence showing that many S100 proteins have multiple binding partners with diverse mode of interaction with different targets. In addition to S100 proteins (such as S100A1,-3,-4,-6,-7,-10,-11,and -13), this group includes the ''fused'' gene family, a group of calcium binding S100-related proteins. The ''fused'' gene family includes multifunctional epidermal differentiation proteins - profilaggrin, trichohyalin, repetin, hornerin, and cornulin; functionally these proteins are associated with keratin intermediate filaments and partially crosslinked to the cell envelope. These ''fused'' gene proteins contain N-terminal sequence with two Ca-binding EF-hands motif, which may be associated with calcium signaling in epidermal cells and autoprocessing in a calcium-dependent manner. In contrast to S100 proteins, "fused" gene family proteins contain an extraordinary high number of almost perfect peptide repeats with regular array of polar and charged residues similar to many known cell envelope proteins.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 1050115333  58 DKDGNGY-ISAAELRHVMTN-----LGEKLTDEEVDEMIREADIDGDGQVNYEEFVQMM 110
Cdd:cd00213    19 GKEGDKDtLSKKELKELLETelpnfLKNQKDPEAVDKIMKDLDVNKDGKVDFQEFLVLI 77

EF-hand domain pair;

                          10        20        30
                  ....*....|....*....|....*....|....*
gi 1050115333   3 SLGQNPTEAELQDMINEVDADGNGTIDFPEFLTMM 37
Cdd:pfam13499  32 EEGEPLSDEEVEELFKEFDLDKDGRISFEEFLELY 66

XopAW family type III secretion system calcium-binding effector;

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*...
gi 1050115333  54 FRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMIREADIDGDGQVNYEEFVQMMT 111
Cdd:NF041410   33 FAKLDSDGDGSVSQDELSSALSSKSDDGSLIDLSELFSDLDSDGDGSLSSDELAAAAP 90

EF-hand domain; This domain is found predominantly in DJ binding proteins.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1050115333  36 MMARKMKDTDSE-EEIREAFRVFDKDGNGYISAAELRHVMTNLGEKLTDEEVDEMIREADIDGDGQVNYEEFVQMMTAK 113
Cdd:pfam08976   7 ILARLHKAVASHyHAITQEFENFDTLKSNTISRDEFRAICNRHIQILTDEQFDRLWNELPVNAKGRLKYPDFLSKFSIE 85

EF-hand motif found in Saccharomyces cerevisiae phospholipase C-1 (ScPlc1p) and similar proteins; This family represents a group of putative phosphoinositide-specific phospholipase C (PI-PLC, EC 3.1.4.11) encoded by PLC1 genes from yeasts, which are homologs of the delta isoforms of mammalian PI-PLC in terms of overall sequence similarity and domain organization. Mammalian PI-PLC is a signaling enzyme that hydrolyzes the membrane phospholipids phosphatidylinositol-4,5-bisphosphate (PIP2) to generate two important second messengers in eukaryotic signal transduction cascades, inositol 1,4,5-trisphosphate (InsP3) and diacylglycerol (DAG). InsP3 triggers inflow of calcium from intracellular stores, while DAG, together with calcium, activates protein kinase C, which then phosphorylates other molecules, leading to altered cellular activity. Calcium is required for the catalysis. The prototype of this family is protein Plc1p (also termed 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase 1) encoded by PLC1 genes from Saccharomyces cerevisiae. ScPlc1p contains both highly conserved X- and Y- regions of PLC catalytic core domain, as well as a presumptive EF-hand like calcium binding motif. Experiments show that ScPlc1p displays calcium dependent catalytic properties with high similarity to those of the mammalian PLCs, and plays multiple roles in modulating the membrane/protein interactions in filamentation control. CaPlc1p encoded by CAPLC1 from the closely related yeast Candida albicans, an orthologue of S. cerevisiae Plc1p, is also included in this group. Like SCPlc1p, CaPlc1p has conserved presumptive catalytic domain, shows PLC activity when expressed in E. coli, and is involved in multiple cellular processes. There are two other gene copies of CAPLC1 in C. albicans, CAPLC2 (also named as PIPLC) and CAPLC3. Experiments show CaPlc1p is the only enzyme in C. albicans which functions as PLC. The biological functions of CAPLC2 and CAPLC3 gene products must be clearly different from CaPlc1p, but their exact roles remain unclear. Moreover, CAPLC2 and CAPLC3 gene products are more similar to extracellular bacterial PI-PLC than to the eukaryotic PI-PLC, and they are not included in this subfamily.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1050115333   2 RSLGQNPTEAELQDMINEVDADGNGTIDFPEFLTMMARkMKDtdsEEEIREAFRVFDKDGNGYISAAELRHVMTNL-GEK 80
Cdd:cd16207    29 RRLHINCSESYLRELFDKADTDKKGYLNFEEFQEFVKL-LKR---RKDIKAIFKQLTKPGSDGLTLEEFLKFLRDVqKED 104