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
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSESELQDMINEVDADNNGTIDFPEFLTMMA 54
Cdd:cd00051    10 DKDGDGTISADELKAALKSLGEGLSEEEIDEMIREVDKDGDGKIDFEEFLELMA 63

EF-hand domain pair;

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 1681081153   1 DKDGDGQITTKELGTVMRSL--GQNPSESELQDMINEVDADNNGTIDFPEFLTMM 53
Cdd:pfam13499  12 DSDGDGYLDVEELKKLLRKLeeGEPLSDEEVEELFKEFDLDKDGRISFEEFLELY 66

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 1681081153   65 EIREAFKVFDRDNNGFISAAELRHVMTSI 93
Cdd:smart00054   1 ELKEAFRLFDKDGDGKIDFEEFKDLLKAL 29

XopAW family type III secretion system calcium-binding effector;

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1681081153  25 SESELQDMINEVDADNNGTIDFPEFLTMMARKmKDTDSEEEIREAFKVFDRDNNGFISAAEL 86
Cdd:NF041410   25 SQQFQKQLFAKLDSDGDGSVSQDELSSALSSK-SDDGSLIDLSELFSDLDSDGDGSLSSDEL 85

centrin; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSESELQDMINEVDADNNGTIDFPEFLTMMARKMKDTDSEEEIREAFKVFDRDNNGF 80
Cdd:PTZ00183   27 DTDGSGTIDPKELKVAMRSLGFEPKKEEIKQMIADVDKDGSGKIDFEEFLDIMTKKLGERDPREEILKAFRLFDDDKTGK 106

                          90       100
                  ....*....|....*....|
gi 1681081153  81 ISAAELRHVMTSIGEKLTDD 100
Cdd:PTZ00183  107 ISLKNLKRVAKELGETITDE 126

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 1681081153   1 DKDGDGQITTKELGTVMRSLGQNP-SESELQDMINEVDADNNGTIDFPEFltmmarkmKDTDSE-EEIREAFKVFDRDNN 78
Cdd:cd16180    10 DRDRSGRISAKELQRALSNGDWTPfSIETVRLMINMFDRDRSGTINFDEF--------VGLWKYiQDWRRLFRRFDRDRS 81

                          90       100
                  ....*....|....*....|..
gi 1681081153  79 GFISAAELRHVMTSIGEKLTDD 100
Cdd:cd16180    82 GSIDFNELQNALSSFGYRLSPQ 103

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

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSESELQDMINEVDADNNGTIDFPEFLTMMARKmkdTDSEEEIREAFKVFDRDNNGF 80
Cdd:COG5126    43 DTDGDGRISREEFVAGMESLFEATVEPFARAAFDLLDTDGDGKISADEFRRLLTAL---GVSEEEADELFARLDTDGDGK 119

                          90
                  ....*....|..
gi 1681081153  81 ISAAELRHVMTS 92
Cdd:COG5126   120 ISFEEFVAAVRD 131

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 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSESE-LQDMINEVDADNNGTIDFPEFLTMMarkmkdtDSEEEIREAFKVFDRDNNG 79
Cdd:cd16183    10 DKDRSGQISATELQQALSNGTWTPFNPEtVRLMIGMFDRDNSGTINFQEFAALW-------KYITDWQNCFRSFDRDNSG 82

                          90       100
                  ....*....|....*....|.
gi 1681081153  80 FISAAELRHVMTSIGEKLTDD 100
Cdd:cd16183    83 NIDKNELKQALTSFGYRLSDQ 103

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 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSESELQDMINEVDADNNGTIDFPEFLTMMARKMkdtdSEEEIREAFKVFDRDNNGF 80
Cdd:cd15898    10 DKDGDGKLSLKEIKKLLKRLNIRVSEKELKKLFKEVDTNGDGTLTFDEFEELYKSLT----ERPELEPIFKKYAGTNRDY 85

                  ....*...
gi 1681081153  81 ISAAELRH 88
Cdd:cd15898    86 MTLEEFIR 93

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 1681081153   1 DKDGDGQITTKEL-GTVMRSLGQNPSESELQDMINEVDADNNGTIDFPEFltmmarkmkdtdSE-----EEIREAFKVFD 74
Cdd:cd16184    10 DRDRSGKISAKELqQALVNGNWSHFNDETCRLMIGMFDKDKSGTIDIYEF------------QAlwnyiQQWKQVFQQFD 77

                          90       100
                  ....*....|....*....|....*
gi 1681081153  75 RDNNGFISAAELRHVMTSIGEKLTD 99
Cdd:cd16184    78 RDRSGSIDENELHQALSQMGYRLSP 102

centrin; Provisional

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*.
gi 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSESELQDMINEVDADNNGTIDFPEFLTMMARK 56
Cdd:PTZ00183  100 DDDKTGKISLKNLKRVAKELGETITDEELQEMIDEADRNGDGEISEEEFYRIMKKT 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
                  ....*....|....*....|....*....|....*.
gi 1681081153  65 EIREAFKVFDRDNNGFISAAELRHVMTSIGEKLTDD 100
Cdd:cd00051     1 ELREAFRLFDKDGDGTISADELKAALKSLGEGLSEE 36

EF-hand domain pair;

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|...
gi 1681081153   4 GDGQITTKELGTVMRSLG-QNPSESELQDMINEVDADNNGTIDFPEFLTMMAR 55
Cdd:pfam13833   1 EKGVITREELKRALALLGlKDLSEDEVDILFREFDTDGDGYISFDEFCVLLER 53

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 1681081153   3 DGDGQITTKELGTVMRSlgQNPSESELQD---------MINEVDADNNGTIDFPEFLTMMARKmkdtdseEEIREAFKVF 73
Cdd:cd16182    11 GEDEEIDAVELQKLLNA--SLLKDMPKFDgfsletcrsLIALMDTNGSGRLDLEEFKTLWSDL-------KKWQAIFKKF 81

                          90       100
                  ....*....|....*....|....
gi 1681081153  74 DRDNNGFISAAELRHVMTSIGEKL 97
Cdd:cd16182    82 DTDRSGTLSSYELRKALESAGFHL 105

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 1681081153   65 EIREAFKVFDRDNNGFISAAELRHVMTSI 93
Cdd:smart00054   1 ELKEAFRLFDKDGDGKIDFEEFKDLLKAL 29

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 1681081153   1 DKDGDGQITTKELGTVMRSL-----GQNPSESELQDMINEV----DADNNGTIDFPEFLTMMA---------RKMKDTDS 62
Cdd:cd15902     9 DADGNGYIEGKELDSFLRELlkalnGKDKTDDEVAEKKKEFmekyDENEDGKIEIRELANILPteenflllfRREQPLIS 88

                          90       100
                  ....*....|....*....|....*...
gi 1681081153  63 EEEIREAFKVFDRDNNGFISAAELRHVM 90
Cdd:cd15902    89 SVEFMKIWRKYDTDGSGFIEAKELKGFL 116

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
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1681081153  32 MINEVDADNNGTIDFPEF--LTMMARKMKDtdseeeireAFKVFDRDNNGFISAAELRHVMTSIGEKLT 98
Cdd:cd16196    46 MVAMMDVDRSGKLGFEEFkkLWEDLRSWKR---------VFKLFDTDGSGSFSSFELRNALNSAGFRLS 105

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 1681081153   4 GDGQITTKELGTVMRSLGQNPSESEL-----QDMINEVDADNNGTIDFPEFlTMMARKMKDtdseeeIREAFKVFDRDNN 78
Cdd:cd15897    12 DDGEISATELQQALSNVGWTHFDLGFsletcRSMIAMMDRDHSGKLNFSEF-KGLWNYIKA------WQEIFRTYDTDGS 84

                          90       100
                  ....*....|....*....|.
gi 1681081153  79 GFISAAELRHVMTSIGEKLTD 99
Cdd:cd15897    85 GTIDSNELRQALSGAGYRLSE 105

EF-hand motif found in phosphoinositide phospholipase C eta (PI-PLC-eta); PI-PLC-eta isozymes represent a class of neuron-specific metazoan PI-PLCs that are most abundant in the brain, particularly in the hippocampus, habenula, olfactory bulb, cerebellum, and throughout the cerebral cortex. They are phosphatidylinositol 4,5-bisphosphate-hydrolyzing enzymes that are more sensitive to Ca2+ than other PI-PLC isozymes. They function as calcium sensors activated by small increases in intracellular calcium concentrations. They are also activated through G-protein-coupled receptor (GPCR) stimulation, and further mediate GPCR signalling pathways. PI-PLC-eta isozymes contain an N-terminal pleckstrin homology (PH) domain, four atypical EF-hand motifs, a PLC catalytic core domain, a C2 domain, and a unique C-terminal tail that terminates with a PDZ-binding motif, a potential interaction site for other signaling proteins. The PLC catalytic core domain is a TIM barrel with two highly conserved regions (X and Y) split by a highly degenerate linker sequence. The C-terminal tail harbors a number of proline-rich motifs which may interact with SH3 (Src homology 3) domain-containing proteins, as well as many serine/threonine residues, suggesting possible regulation of interactions by protein kinases/phosphatases. There are two PI-PLC-eta isozymes (1-2). Aside from the PI-PLC-eta isozymes identified in mammals, their eukaryotic homologs are also present in this family.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*...
gi 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSESELQDMINEVDADNN-GTIDFPEFLT---MMA 54
Cdd:cd16205    10 DKNGDGLLSIGEILQLMHKLNVNLPRRKVRQMFKEADTDDNqGTLDFEEFCAfykMMS 67

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 1681081153   1 DKDGDGQITTKELGTVMRSL----GQNPSESELQDMIN----EVDADNNGTIDFPE----------FLTMMARKMKDTDS 62
Cdd:cd15902   100 DTDGSGFIEAKELKGFLKDLllknKKHVSPPKLDEYTKlilkEFDANKDGKLELDEmakllpvqenFLLKFQILGAMDLT 179

                          90       100       110
                  ....*....|....*....|....*....|....
gi 1681081153  63 EEEIREAFKVFDRDNNGFISAAELRHVMTSIGEK 96
Cdd:cd15902   180 KEDFEKVFEHYDKDNNGVIEGNELDALLKDLLEK 213

XopAW family type III secretion system calcium-binding effector;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSESELQDMINEVDADNNGTIDFPEFLTMMA------RKMKDTDSEEEIreaFKVFD 74
Cdd:NF041410   37 DSDGDGSVSQDELSSALSSKSDDGSLIDLSELFSDLDSDGDGSLSSDELAAAAPppppppDQAPSTELADDL---LSALD 113

                          90       100
                  ....*....|....*....|
gi 1681081153  75 RDNNGFISAAELRHVMTSIG 94
Cdd:NF041410  114 TDGDGSISSDELSAGLTSAG 133

EF-hand motif found in phosphoinositide phospholipase C eta 2 (PI-PLC-eta2); PI-PLC-eta2, also termed 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase eta-2, or phosphoinositide phospholipase C-like 4, or phospholipase C-like protein 4 (PLC-L4), or phospholipase C-eta-2 (PLC-eta2), is a neuron-specific PI-PLC that is most abundant in the brain, particularly in the hippocampus, habenula, olfactory bulb, cerebellum, and throughout the cerebral cortex. It is also expressed in the pituitary gland, pineal gland, retina, and lung, as well as in neuroendocrine cells. PI-PLC-eta2 has been implicated in the regulation of neuronal differentiation/maturation. It is required for retinoic acid-stimulated neurite growth. It may also in part function downstream of G-protein-coupled receptors and play an important role in the formation and maintenance of the neuronal network in the postnatal brain. Moreover, PI-PLC-eta2 acts as a Ca2+ sensor that shows a canonical EF-loop directing Ca2+-sensitivity and thus can amplify transient Ca2+ signals. Its activation can be triggered either by intracellular calcium mobilization or by G beta-gamma signaling. PI-PLC-eta2 contains an N-terminal pleckstrin homology (PH) domain, four atypical EF-hand motifs, a PLC catalytic core domain, a C2 domain, and a unique C-terminal tail that terminates with a PDZ-binding motif, a potential interaction site for other signaling proteins. The PLC catalytic core domain is a TIM barrel with two highly conserved regions (X and Y) split by a highly degenerate linker sequence. The C-terminal tail harbors a number of proline-rich motifs which may interact with SH3 (Src homology 3) domain-containing proteins, as well as many serine/threonine residues, suggesting possible regulation of interactions by protein kinases/phosphatases.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|
gi 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSESELQDMINEVDADNN-GTIDFPEFLT---MMARK 56
Cdd:cd16221    10 DKNGDGSLSIGEVLQLLHKLNVNLPRQKVKQMFKEADTDDNqGTLGFEEFCAfykMMSTR 69

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 1681081153  18 RSLGQNPSESELQDMINEVDADNNGTIDFPEFLTMMARkMKDtdsEEEIREAFKVFDRDNNGFISAAELRHVMTSI-GEK 96
Cdd:cd16207    29 RRLHINCSESYLRELFDKADTDKKGYLNFEEFQEFVKL-LKR---RKDIKAIFKQLTKPGSDGLTLEEFLKFLRDVqKED 104

                  ....
gi 1681081153  97 LTDD 100
Cdd:cd16207   105 VDRE 108

Penta-EF hand, calcium binding motifs, found in sorcin; 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. The up-regulation of sorcin is correlated with a number of cancer types, including colorectal, gastric and breast cancer. It may represent a therapeutic target for reversing tumor multidrug resistance (MDR). Sorcin participates in the regulation of calcium homeostasis in cells and is necessary for the activation of mitosis and cytokinesis. It enhances metastasis and promotes epithelial-to-mesenchymal transition of colorectal cancer. Moreover, sorcin has been implicated in the regulation of intracellular Ca2+ cycling and cardiac excitation-contraction coupling. It displays the anti-apoptotic properties via the modulation of mitochondrial Ca2+ handling in cardiac myocytes. It can target and activate the sarcolemmal Na+/Ca2+ exchanger (NCX1) in cardiac muscle. Meanwhile, sorcin modulates cardiac L-type Ca2+ current by functional interaction with the alpha1C subunit. It also associates with calcium/calmodulin-dependent protein kinase IIdeltaC (CaMKIIdelta(C)) and further modulates ryanodine receptor (RyR) function in cardiac myocytes. Furthermore, sorcin may act as a Ca2+ sensor for glucose-induced nuclear translocation and the activation of carbohydrate-responsive element-binding protein (ChREBP)-dependent genes. As a mitochondrial chaperone TRAP1 interactor, sorcin involves in mitochondrial metabolism through the TRAP1 pathway. In addition, sorcin may regulate the inhibition of type I interferon response in cells through interacting with foot-and-mouth disease virus (FMDV) VP1. Sorcin 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.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1681081153   5 DGQITTKELGTVMR----SLGQNPSESE-LQDMINEVDADNNGTIDFPEFLTMMArkmkdtdSEEEIREAFKVFDRDNNG 79
Cdd:cd16187    13 DGQIDADELQRCLTqsgiAGGYKPFNLEtCRLMISMLDRDMSGTMGFNEFKELWA-------VLNGWRQHFISFDSDRSG 85

                          90
                  ....*....|....*....
gi 1681081153  80 FISAAELRHVMTSIGEKLT 98
Cdd:cd16187    86 TVDPQELQKALTTMGFRLS 104

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 1681081153   1 DKDGDGQITTKELGTVMrslgqNPSESE------LQDMINEVDADNNGTIDFPEFLTMMARK---MKDTDSEEEIREAFK 71
Cdd:cd16226   129 DQDGDGKLTKEEFTAFL-----HPEEFPhmrdivVQETLEDIDKNKDGFISLEEYIGDMYRDddeEEDPDWVKSEREQFK 203

                          90
                  ....*....|....*...
gi 1681081153  72 VF-DRDNNGFISAAELRH 88
Cdd:cd16226   204 EFrDKNKDGKMDREEVKD 221

EF-hand, calcium binding motif, found in calbindin (CB); CB, also termed calbindin D28, or D-28K, or avian-type vitamin D-dependent calcium-binding protein, is a unique intracellular calcium binding protein that functions as both a calcium sensor and buffer in eukaryotic cells, which undergoes a conformational change upon calcium binding and protects cells against insults of high intracellular calcium concentration. CB is highly expressed in brain and sensory neurons. It plays essential roles in neural functioning, altering synaptic interactions in the hippocampus, modulating calcium channel activity, calcium transients, and intrinsic neuronal firing activity. It prevents a neuronal death, as well as maintains and controls calcium homeostasis. CB also modulates the activity of proteins participating in the development of neurodegenerative disorders such as Alzheimer's disease, Huntington's disease, and bipolar disorder. Moreover, CB interacts with Ran-binding protein M, a protein known to involve in microtubule function. It also interacts with alkaline phosphatase and myo-inositol monophosphatase, as well as caspase 3, an enzyme that plays an important role in the regulation of apoptosis. CB contains six EF-hand motifs in a single globular domain, where EF-hands 1, 3, 4, 5 bind four calcium ions with high affinity.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSES------ELQDMINEVDADNNGTIDFPE----------FLTMMARKMKdtdSEE 64
Cdd:cd16176     9 DNDGNGYIEGKELQSFIQELQQARKKAglelsdQMKAFVDQYGQSTDGKIGIVElaqilpteenFLLFFRQQLK---SSE 85

                          90       100       110
                  ....*....|....*....|....*....|..
gi 1681081153  65 EIREAFKVFDRDNNGFISAAELRHVMTSIGEK 96
Cdd:cd16176    86 EFMQTWRKYDADHSGFIEADELKSFLKDLLKK 117

XopAW family type III secretion system calcium-binding effector;

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1681081153  25 SESELQDMINEVDADNNGTIDFPEFLTMMARKmKDTDSEEEIREAFKVFDRDNNGFISAAEL 86
Cdd:NF041410   25 SQQFQKQLFAKLDSDGDGSVSQDELSSALSSK-SDDGSLIDLSELFSDLDSDGDGSLSSDEL 85

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        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSESELQDMINEVDADNNGTIDFPEFLTMMARKMKdtdsEEEIREAFKVFDrDNNGF 80
Cdd:cd16202    10 DKNGDGKLSFKECKKLLKKLNVKVDKDYAKKLFQEADTSGEDVLDEEEFVQFYNRLTK----RPEIEELFKKYS-GDDEA 84

                          90
                  ....*....|.
gi 1681081153  81 ISAAELRHVMT 91
Cdd:cd16202    85 LTVEELRRFLQ 95

centrin; Provisional

                          10        20        30
                  ....*....|....*....|....*....|....
gi 1681081153  61 DSEEEIREAFKVFDRDNNGFISAAELRHVMTSIG 94
Cdd:PTZ00183   14 DQKKEIREAFDLFDTDGSGTIDPKELKVAMRSLG 47

EF-hand, calcium binding motif, found in homologs of mammalian apoptosis-linked gene 2 protein (ALG-2); The family includes some homologs of mammalian apoptosis-linked gene 2 protein (ALG-2) mainly found in lower eukaryotes, such as a parasitic protist Leishmarua major and a cellular slime mold Dictyostelium discoideum. These homologs contains five EF-hand motifs. Due to the presence of unfavorable residues at the Ca2+-coordinating positions, their non-canonical EF4 and EF5 hands may not bind Ca2+. Two Dictyostelium PEF proteins are the prototypes of this family. They may bind to cytoskeletal proteins and/or signal-transducing proteins localized to detergent-resistant membranes named lipid rafts, and occur as monomers or weak homo- or heterodimers like ALG-2. They can serve as a mediator for Ca2+ signaling-related Dictyostehum programmed cell death (PCD).

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSESELQDMINEVDADNNGTIDFPEFLTMMARKMKdtdseeeIREAFKVFDRDNNGF 80
Cdd:cd16185    76 DTSRSGRLDANEVHEALAASGFQLDPPAFQALFRKFDPDRGGSLGFDDYIELCIFLAS-------ARNLFQAFDRQRTGR 148

                  ..
gi 1681081153  81 IS 82
Cdd:cd16185   149 VT 150

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 1681081153   1 DKDGDGQITTKELGTVMRSLGQNPSEsELQDMINEVDADNNGTIDFPEFLTMMARKmkdtdseEEIREAFKVFDRDNNGF 80
Cdd:cd15897    80 DTDGSGTIDSNELRQALSGAGYRLSE-QTYDIIIRRYDRGRGNIDFDDFIQCCVRL-------QRLTDAFRRYDKDQDGQ 151

                  .
gi 1681081153  81 I 81
Cdd:cd15897   152 I 152

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
                  ....*....|....*....|....*....|....*....|....*....
gi 1681081153   1 DKDGDGQITTKELGTVMRSLGQnpSESELQDMINEVDADNNGTIDFPEF 49
Cdd:cd00052     9 DPDGDGLISGDEARPFLGKSGL--PRSVLAQIWDLADTDKDGKLDKEEF 55

calmodulin; Provisional

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 1681081153  57 MKDTDSEEEI---REAFKVFDRDNNGFISAAELRHVMTSIGEKLTD 99
Cdd:PTZ00184    1 MADQLTEEQIaefKEAFSLFDKDGDGTITTKELGTVMRSLGQNPTE 46