K homology (KH) RNA-binding domain, type I; KH binds single-stranded RNA or DNA. It is found in a wide variety of proteins including ribosomal proteins, transcription factors and post-transcriptional modifiers of mRNA. There are two different KH domains that belong to different protein folds, but they share a single KH motif. The KH motif is folded into a beta alpha alpha beta unit. In addition to the core, type II KH domains (e.g. ribosomal protein S3) include an N-terminal extension and type I KH domains (e.g. hnRNP K) contain a C-terminal extension. Some KH-I superfamily members contain a divergent KH domain that lacks the RNA-binding GXXG motif. Some others have a mutated GXXG motif which may or may not have nucleic acid binding ability.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 255725734  99 INYRVLVSAKEAGCLIGTNGQVIDSIRGETNTKAGISRLVPGSHERILTVSGKLDDCAKALSYFAQALVN 168
Cdd:cd22455    1 LTLRALVSSKEAAVIIGKGGENIARLRATTGVKAGVSKVVPGVHDRVLTVSGPLEGVAKAFGLIARTLNE 70

K homology (KH) RNA-binding domain, type I; KH binds single-stranded RNA or DNA. It is found in a wide variety of proteins including ribosomal proteins, transcription factors and post-transcriptional modifiers of mRNA. There are two different KH domains that belong to different protein folds, but they share a single KH motif. The KH motif is folded into a beta alpha alpha beta unit. In addition to the core, type II KH domains (e.g. ribosomal protein S3) include an N-terminal extension and type I KH domains (e.g. hnRNP K) contain a C-terminal extension. Some KH-I superfamily members contain a divergent KH domain that lacks the RNA-binding GXXG motif. Some others have a mutated GXXG motif which may or may not have nucleic acid binding ability.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 255725734 307 TLTFPNDIVGALIGKQGARINGVRKITGATISISD--GGEDERIFTITGSSQAVEKAKQMIYQ 367
Cdd:cd22439    5 EITIPNDLIGCIIGKGGTKINEIRQLSGATIKIANseDGSTERSVTITGTPEAVSLAQYLINA 67

first type I K homology (KH) RNA-binding domain found in Schizosaccharomyces pombe RNA-binding protein Rnc1 and similar proteins; Rnc1, also called RNA-binding protein that suppresses calcineurin deletion 1, is an RNA-binding protein that acts as an important regulator of the posttranscriptional expression of the MAPK phosphatase Pmp1 in fission yeast. It binds and stabilizes pmp1 mRNA and hence acts as a negative regulator of pmk1 signaling. Overexpression of Rnc1 suppresses the Cl(-) sensitivity of calcineurin deletion. The nuclear export of Rnc1 requires mRNA-binding ability and the mRNA export factor Rae1. Rnc1 contains three K-homology (KH) RNA-binding domains. The model corresponds to the first one.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 255725734  99 INYRVLVSAKEAGCLIGTNGQVIDSIRGETNTKAGISRLVPGSHERILTVSGKLDDCAKALSYFAQALVN 168
Cdd:cd22455    1 LTLRALVSSKEAAVIIGKGGENIARLRATTGVKAGVSKVVPGVHDRVLTVSGPLEGVAKAFGLIARTLNE 70

third type I K homology (KH) RNA-binding domain found in the family of poly(C)-binding proteins (PCBPs); The PCBP family, also known as hnRNP E family, comprises four members, PCBP1-4, which are RNA-binding proteins that interact in a sequence-specific manner with single-stranded poly(C) sequences. They are mainly involved in various posttranscriptional regulations, including mRNA stabilization or translational activation/silencing. Besides, PCBPs may share iron chaperone activity. PCBPs contain three K-homology (KH) RNA-binding domains. The model corresponds to the third one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 255725734 307 TLTFPNDIVGALIGKQGARINGVRKITGATISISD--GGEDERIFTITGSSQAVEKAKQMIYQ 367
Cdd:cd22439    5 EITIPNDLIGCIIGKGGTKINEIRQLSGATIKIANseDGSTERSVTITGTPEAVSLAQYLINA 67

K homology RNA-binding domain;

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 255725734   304 KKATLTFPNDIVGALIGKQGARINGVRKITGATISISDGGEDERIFTITGSSQAVEKAKQMIYQ 367
Cdd:smart00322   3 VTIEVLIPADKVGLIIGKGGSTIKKIEEETGVKIDIPGPGSEERVVEITGPPENVEKAAELILE 66

K homology RNA-binding domain;

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 255725734    99 INYRVLVSAKEAGCLIGTNGQVIDSIRGETNTKAGISRlvPGSHERILTVSGKLDDCAKALSYFAQAL 166
Cdd:smart00322   3 VTIEVLIPADKVGLIIGKGGSTIKKIEEETGVKIDIPG--PGSEERVVEITGPPENVEKAAELILEIL 68

polynucleotide phosphorylase/polyadenylase; Provisional

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 255725734 307 TLTFPNDIVGALIGKQGARINGVRKITGATISISDGGedeRIFtITGSSQ-AVEKAKQMI 365
Cdd:PRK11824 557 TIKIPPDKIRDVIGPGGKTIREITEETGAKIDIEDDG---TVK-IAATDGeAAEAAKERI 612

first type I K homology (KH) RNA-binding domain found in Schizosaccharomyces pombe RNA-binding protein Rnc1 and similar proteins; Rnc1, also called RNA-binding protein that suppresses calcineurin deletion 1, is an RNA-binding protein that acts as an important regulator of the posttranscriptional expression of the MAPK phosphatase Pmp1 in fission yeast. It binds and stabilizes pmp1 mRNA and hence acts as a negative regulator of pmk1 signaling. Overexpression of Rnc1 suppresses the Cl(-) sensitivity of calcineurin deletion. The nuclear export of Rnc1 requires mRNA-binding ability and the mRNA export factor Rae1. Rnc1 contains three K-homology (KH) RNA-binding domains. The model corresponds to the first one.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 255725734  99 INYRVLVSAKEAGCLIGTNGQVIDSIRGETNTKAGISRLVPGSHERILTVSGKLDDCAKALSYFAQALVN 168
Cdd:cd22455    1 LTLRALVSSKEAAVIIGKGGENIARLRATTGVKAGVSKVVPGVHDRVLTVSGPLEGVAKAFGLIARTLNE 70

third type I K homology (KH) RNA-binding domain found in the family of poly(C)-binding proteins (PCBPs); The PCBP family, also known as hnRNP E family, comprises four members, PCBP1-4, which are RNA-binding proteins that interact in a sequence-specific manner with single-stranded poly(C) sequences. They are mainly involved in various posttranscriptional regulations, including mRNA stabilization or translational activation/silencing. Besides, PCBPs may share iron chaperone activity. PCBPs contain three K-homology (KH) RNA-binding domains. The model corresponds to the third one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 255725734 307 TLTFPNDIVGALIGKQGARINGVRKITGATISISD--GGEDERIFTITGSSQAVEKAKQMIYQ 367
Cdd:cd22439    5 EITIPNDLIGCIIGKGGTKINEIRQLSGATIKIANseDGSTERSVTITGTPEAVSLAQYLINA 67

KH domain; KH motifs bind RNA in vitro. Autoantibodies to Nova, a KH domain protein, cause paraneoplastic opsoclonus ataxia.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 255725734  307 TLTFPNDIVGALIGKQGARINGVRKITGATISI--SDGGEDERIFTITGSSQAVEKAKQMIYQ 367
Cdd:pfam00013   3 EILVPSSLVGLIIGKGGSNIKEIREETGAKIQIppSESEGNERIVTITGTPEAVEAAKALIEE 65

K homology RNA-binding domain;

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 255725734   304 KKATLTFPNDIVGALIGKQGARINGVRKITGATISISDGGEDERIFTITGSSQAVEKAKQMIYQ 367
Cdd:smart00322   3 VTIEVLIPADKVGLIIGKGGSTIKKIEEETGVKIDIPGPGSEERVVEITGPPENVEKAAELILE 66

first type I K homology (KH) RNA-binding domain found in the FUBP family RNA/DNA-binding proteins; The far upstream element-binding protein (FUBP) family includes FUBP1-3. FUBP1, also called FBP, or FUSE-binding protein 1, or DNA helicase V, or DH V, binds RNA and single-stranded DNA (ssDNA) and may act both as activator and repressor of transcription. It regulates MYC expression by binding to a single-stranded far-upstream element (FUSE) upstream of the MYC promoter. FUBP2, also called FUSE-binding protein 2, or KH type-splicing regulatory protein (KSRP), or p75, is a single-strand nucleic acid binding protein implicated in a variety of cellular processes, including splicing in the nucleus, mRNA decay, maturation of miRNA, and transcriptional control of proto-oncogenes such as c-myc. It regulates the stability and/or translatability of many mRNA species, encoding immune-relevant proteins, either by binding to AU-rich elements (AREs) of mRNA 3'UTR or by facilitating miRNA biogenesis to target mRNA. FUBP3, also called FUSE-binding protein 3, or MARTA2, was previously shown to mediate dendritic targeting of MAP2 mRNA in neurons. It may interact with single-stranded DNA from the far-upstream element (FUSE) and activate gene expression. It is required for beta-actin mRNA localization. It also interacts with fibroblast growth factor 9 (FGF9) 3'-UTR UG repeats and positively controls FGF9 expression through increasing translation of FGF9 mRNA. FUBP proteins contain four K-homology (KH) RNA-binding domains. The model corresponds to the first one.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*....
gi 255725734 311 PNDIVGALIGKQGARINGVRKITGATISIS--DGGEDERIFTITGSSQAVEKAKQMIYQ 367
Cdd:cd22396    8 PDKMVGLIIGRGGEQINRLQAESGAKIQIApdSGGLPERPCTLTGTPDAIETAKRLIDQ 66

type I K homology (KH) RNA-binding domain found in Mask family proteins; The Mask family includes Drosophila melanogaster ankyrin repeat and KH domain-containing protein Mask, and its mammalian homologues Mask1/ANKHD1 and Mask2/ANKRD17. Mask, also called multiple ankyrin repeat single KH domain-containing protein, is a large ankyrin repeat and KH domain-containing protein involved in Drosophila receptor tyrosine kinase signaling. It acts as a mediator of receptor tyrosine kinase (RTK) signaling and may act either downstream of MAPK or transduce signaling through a parallel branch of the RTK pathway. Mask is required for the development and organization of indirect flight muscle sarcomeres by regulating the formation of M line and H zone and the correct assembly of thick and thin filaments in the sarcomere. Mask1/ANKHD1, also called HIV-1 Vpr-binding ankyrin repeat protein, or multiple ankyrin repeats single KH domain, or Hmask, is highly expressed in various cancer tissues and is involved in cancer progression, including proliferation and invasion. Mask2/ANKRD17, also called ankyrin repeat protein 17, or gene trap ankyrin repeat protein (GTAR), or serologically defined breast cancer antigen NY-BR-16, is a ubiquitously expressed ankyrin factor essential for the vascular integrity during embryogenesis. It may be directly involved in the DNA replication process and play pivotal roles in cell cycle and DNA regulation. It is also involved in innate immune defense against bacteria and viruses.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 255725734 308 LTFPNDIVGALIGKQGARINGVRKITGATISI--SDGGEDERIFTITGSSQAVEKAKQMIYQ 367
Cdd:cd22404    5 VTVPNSAISRVIGRGGCNINAIREVSGAHIEIdkQKGEQGDRRITIKGSADATRQAAQLINA 66

first type I K homology (KH) RNA-binding domain found in tudor and KH domain-containing protein (TDRKH) and similar proteins; TDRKH, also called tudor domain-containing protein 2 (TDRD2), is a mitochondria-anchored RNA-binding protein that is required for spermatogenesis and involved in piRNA biogenesis. It specifically recruits MIWI, but not MILI, to engage the piRNA pathway. TDRKH contains two K-homology (KH) RNA-binding domains and one tudor domain, which are involved in binding to RNA or single-strand DNA. The model corresponds to the first one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 255725734 311 PNDIVGALIGKQGARINGVRKITGATI----SISDGGEDERIFTITGSSQAVEKAKQMIYQ 367
Cdd:cd22428   12 PREAVGLIIGRQGATIKQIQKETGARIdfkdEGSGGELPERVLLIQGNPVQAQRAEEAIHQ 72

third type I K homology (KH) RNA-binding domain found in poly(rC)-binding protein 3 (PCBP3) and similar proteins; PCBP3, also called alpha-CP3, or PCBP3-overlapping transcript, or PCBP3-overlapping transcript 1, or heterogeneous nuclear ribonucleoprotein E3, or hnRNP E3, is a single-stranded nucleic acid binding protein that binds preferentially to oligo dC. It can function as a repressor dependent on binding to single-strand and double-stranded poly(C) sequences. PCBP3 contains three K-homology (KH) RNA-binding domains. The model corresponds to the third one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 255725734 308 LTFPNDIVGALIGKQGARINGVRKITGATISISDG--GEDERIFTITGSSQAVEKAKQMI 365
Cdd:cd22522   13 LTIPNDLIGCIIGRQGTKINEIRQMSGAQIKIANAteGSSERQITITGSPANISLAQYLI 72

third type I K homology (KH) RNA-binding domain found in poly(rC)-binding protein 1 (PCBP1) and similar proteins; The family includes PCBP1 (also called alpha-CP1, or heterogeneous nuclear ribonucleoprotein E1, or hnRNP E1, or nucleic acid-binding protein SUB2.3) and PCBP2 (also called alpha-CP2, or heterogeneous nuclear ribonucleoprotein E2, or hnRNP E2). They are single-stranded nucleic acid binding proteins that bind preferentially to oligo dC. They act as iron chaperones for ferritin. In case of infection by poliovirus, PCBP1 plays a role in initiation of viral RNA replication in concert with the viral protein 3CD. PCBP2 is a major cellular poly(rC)-binding protein. It also binds poly(rU). PCBP2 negatively regulates cellular antiviral responses mediated by MAVS signaling. It acts as an adapter between MAVS and the E3 ubiquitin ligase ITCH, therefore triggering MAVS ubiquitination and degradation. PCBP2 forms a metabolon with the heme oxygenase 1/cytochrome P450 reductase complex for heme catabolism and iron transfer. Both PCBP1 and PCBP2 contain three K-homology (KH) RNA-binding domains. The model corresponds to the third one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 255725734 308 LTFPNDIVGALIGKQGARINGVRKITGATISISD--GGEDERIFTITGSSQAVEKAKQMI 365
Cdd:cd22521    9 LTIPNDLIGCIIGRQGAKINEIRQMSGAQIKIANpvEGSTDRQVTITGSAASISLAQYLI 68

second type I K homology (KH) RNA-binding domain found in Arabidopsis thaliana RNA-binding KH domain-containing protein PEPPER and similar proteins; The family includes a group of plant RNA-binding KH domain-containing proteins, such as PEPPER, flowering locus K homology domain protein (FLK), RNA-binding KH domain-containing protein RCF3 and KH domain-containing protein HEN4. PEPPER regulates vegetative and gynoecium development. It acts as a positive regulator of the central floral repressor FLOWERING LOCUS C. In concert with HUA2, PEPPER antagonizes FLK by positively regulating FLC probably at transcriptional and post-transcriptional levels, and thus acts as a negative regulator of flowering. FLK, also called flowering locus KH domain protein, regulates positively flowering by repressing FLC expression and post-transcriptional modification. PEPPER and FLK contain three K-homology (KH) RNA-binding domains. RCF3, also called protein ENHANCED STRESS RESPONSE 1 (ESR1), or protein HIGH OSMOTIC STRESS GENE EXPRESSION 5 (HOS5), or protein REGULATOR OF CBF GENE EXPRESSION 3, or protein SHINY 1 (SHI1), acts as negative regulator of osmotic stress-induced gene expression. It is involved in the regulation of thermotolerance responses under heat stress. It functions as an upstream regulator of heat stress transcription factor (HSF) genes. HEN4, also called protein HUA ENHANCER 4, plays a role in floral reproductive organ identity in the third whorl and floral determinacy specification by specifically promoting the processing of AGAMOUS (AG) pre-mRNA. It functions in association with HUA1 and HUA2. RCF3 and HEN4 contain five KH RNA-binding domains. The model corresponds to the KH2 domain of PEPPER and FLK, as well as KH2 and KH4 domains of RCF3 and HEN4.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 255725734 315 VGALIGKQGARINGVRKITGATISISDGGE-------DERIFTITGSSQAVEKAKQMIYQ 367
Cdd:cd22460   11 AGSLIGKGGAIIKQIREESGASVRILPEEElppcaspDDRVVQISGEAQAVKKALELVSS 70

second type I K homology (KH) RNA-binding domain found in poly(rC)-binding protein 4 (PCBP4) and similar proteins; PCBP4, also called alpha-CP4, or heterogeneous nuclear ribonucleoprotein E4, or hnRNP E4, is a single-stranded nucleic acid binding protein that binds preferentially to oligo dC. It regulates both basal and stress-induced p21 expression through binding p21 3'-UTR and modulating p21 mRNA stability. It also plays a role in the cell cycle and is implicated in lung tumor suppression. PCBP4 contains three K-homology (KH) RNA-binding domains. The model corresponds to the second one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 255725734 194 LRLLIPNTQMGTLIGSKGARIQQIQSKYNISMIASKSFLPGSNERLVELQGSVDDLYDSLRVISRCLME 262
Cdd:cd22520    4 LRLVIPASQCGSLIGKAGSKIKEIRESTGAQVQVAGDLLPNSTERAVTVSGVPDAIIQCVRQICAVILE 72

second type I K homology (KH) RNA-binding domain found in the family of neuro-oncological ventral antigen (Nova); The family includes two related neuronal RNA-binding proteins, Nova-1 and Nova-2. Nova-1, also called onconeural ventral antigen 1, or paraneoplastic Ri antigen, or ventral neuron-specific protein 1, may regulate RNA splicing or metabolism in a specific subset of developing neurons. It interacts with RNA containing repeats of the YCAY sequence. It is a brain-enriched splicing factor regulating neuronal alternative splicing. Nova-1 is involved in neurological disorders and carcinogenesis. Nova-2, also called astrocytic NOVA1-like RNA-binding protein, is a neuronal RNA-binding protein expressed in a broader central nervous system (CNS) distribution than Nova-1. It functions in neuronal RNA metabolism. NOVA family proteins contain three K-homology (KH) RNA-binding domains. The model corresponds to the second one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 255725734 304 KKATLTFPNDIVGALIGKQGARINGVRKITGATISIS----DGGEDERIFTITGSSQAVEKAKQMIYQ 367
Cdd:cd22436    1 KQVKILVPNSTAGMIIGKGGATIKAIMEQSGARVQISqkpeSINLQERVVTVTGEPEANRKAVSLILQ 68

second type I K homology (KH) RNA-binding domain found in the family of poly(C)-binding proteins (PCBPs); The PCBP family, also known as hnRNP E family, comprises four members, PCBP1-4, which are RNA-binding proteins that interact in a sequence-specific manner with single-stranded poly(C) sequences. They are mainly involved in various posttranscriptional regulations, including mRNA stabilization or translational activation/silencing. Besides, PCBPs may share iron chaperone activity. PCBPs contain three K-homology (KH) RNA-binding domains. The model corresponds to the second one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 255725734 308 LTFPNDIVGALIGKQGARINGVRKITGATISISdgGE-----DERIFTITGSSQAVEKAKQMI 365
Cdd:cd02396    6 LLVPASQCGSLIGKGGSKIKEIRESTGASVQVA--SEmlpnsTERAVTISGSPEAITKCVEQI 66

KH domain; KH motifs bind RNA in vitro. Autoantibodies to Nova, a KH domain protein, cause paraneoplastic opsoclonus ataxia.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 255725734  101 YRVLVSAKEAGCLIGTNGQVIDSIRGETNTKAGISRLVPGSHERILTVSGKLDDCAKAL 159
Cdd:pfam00013   2 VEILVPSSLVGLIIGKGGSNIKEIREETGAKIQIPPSESEGNERIVTITGTPEAVEAAK 60

sixth type I K homology (KH) RNA-binding domain found in vigilin and similar proteins; Vigilin, also called high density lipoprotein-binding protein, or HDL-binding protein, is a ubiquitous and highly conserved RNA-binding protein that shuttles between nucleus and cytoplasm presumably in contact with RNA molecules. It may be involved in chromosome partitioning at mitosis, facilitating translation and tRNA transport, and control of mRNA metabolism, including estrogen-mediated stabilization of vitellogenin mRNA. Vigilin is up-regulated by cholesterol loading of cells and functions to protect cells from over-accumulation of cholesterol. It may play a role in cell sterol metabolism. Disruption of human vigilin impairs chromosome condensation and segregation. Vigilin has a unique structure of 14-15 consecutively arranged, but non-identical K-homology (KH) domains which apparently mediate RNA-protein binding. The model corresponds to the sixth one.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|..
gi 255725734 315 VGALIGKQGARINGVRKITGATISISDGGEDERIFTITGSSQAVEKAKQMIY 366
Cdd:cd02394   13 HGHIIGKGGANIKRIREESGVSIRIPDDEANSDEIRIEGSPEGVKKAKAEIL 64

first type I K homology (KH) RNA-binding domain found in poly(rC)-binding protein 3 (PCBP3) and similar proteins; PCBP3, also called alpha-CP3, or PCBP3-overlapping transcript, or PCBP3-overlapping transcript 1, or heterogeneous nuclear ribonucleoprotein E3, or hnRNP E3, is a single-stranded nucleic acid binding protein that binds preferentially to oligo dC. It can function as a repressor dependent on binding to single-strand and double-stranded poly(C) sequences. PCBP3 contains three K-homology (KH) RNA-binding domains. The model corresponds to the first one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 255725734 315 VGALIGKQGARINGVRKITGATISISDGGEDERIFTITGSSQAVEKAKQMIyqNYKREEE 374
Cdd:cd22516   20 VGSIIGKKGETVKKMREESGARINISEGNCPERIVTITGPTDAIFKAFAMI--AYKFEED 77

third type I K homology (KH) RNA-binding domain found in poly(rC)-binding protein 4 (PCBP4) and similar proteins; PCBP4, also called alpha-CP4, or heterogeneous nuclear ribonucleoprotein E4, or hnRNP E4, is a single-stranded nucleic acid binding protein that binds preferentially to oligo dC. It regulates both basal and stress-induced p21 expression through binding p21 3'-UTR and modulating p21 mRNA stability. It also plays a role in the cell cycle and is implicated in lung tumor suppression. PCBP4 contains three K-homology (KH) RNA-binding domains. The model corresponds to the third one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 255725734 303 TKKATLTFPNDIVGALIGKQGARINGVRKITGATISISD--GGEDERIFTITGSSQAVEKAKQMI 365
Cdd:cd22523    1 TSSQEFLIPNDLIGCVIGRQGSKISEIRQMSGAHIKIGNqtEGTSERHVTITGSPVSITLAQYLI 65

first type I K homology (KH) RNA-binding domain found in far upstream element-binding protein 2 (FUBP2) and similar proteins; FUBP2, also called FUSE-binding protein 2, or KH type-splicing regulatory protein (KSRP), or p75, is a single-strand nucleic acid binding protein implicated in a variety of cellular processes, including splicing in the nucleus, mRNA decay, maturation of miRNA, and transcriptional control of proto-oncogenes such as c-myc. It regulates the stability and/or translatability of many mRNA species, encoding immune-relevant proteins, either by binding to AU-rich elements (AREs) of mRNA 3'UTR or by facilitating miRNA biogenesis to target mRNA. FUBP2 contains four K-homology (KH) RNA-binding domains. The model corresponds to the first one.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*..
gi 255725734 311 PNDIVGALIGKQGARINGVRKITGATISIS--DGGEDERIFTITGSSQAVEKAKQMI 365
Cdd:cd22479    8 PDGMVGLIIGRGGEQINKIQQDSGCKVQISpdSGGLPERSVSLTGSPEAVQKAKMML 64

third type I K homology (KH) RNA-binding domain found in the insulin-like growth factor 2 mRNA-binding protein (IGF2BP) family; The IGF2BP family includes three members: IGF2BP1/IMP-1/ CRD-BP/ VICKZ1, IGF2BP2/IMP-2/ VICKZ2, and IGF2BP3/IMP-3/VICKZ3, which are RNA-binding factors that recruit target transcripts to cytoplasmic protein-RNA complexes (mRNPs). They function by binding to the 5' UTR of the insulin-like growth factor 2 (IGF2) mRNA and regulating IGF2 translation. IGF2BP proteins contain four K-homology (KH) RNA-binding domains which are important in RNA binding and are known to be involved in RNA synthesis and metabolism. The model corresponds to the third one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 255725734 305 KATLTFPNDIVGALIGKQGARINGVRKITGATISIS---DGGEDERIFTITGSSQAVEKAKQMIY 366
Cdd:cd22402    2 TTYLYIPNKAVGAIIGTKGSHIRYIKRFSGASIKIApadSPDAPERKVTITGPPEAQWKAQLCIF 66

tenth type I K homology (KH) RNA-binding domain found in vigilin and similar proteins; Vigilin, also called high density lipoprotein-binding protein, or HDL-binding protein, is a ubiquitous and highly conserved RNA-binding protein that shuttles between nucleus and cytoplasm presumably in contact with RNA molecules. It may be involved in chromosome partitioning at mitosis, facilitating translation and tRNA transport, and control of mRNA metabolism, including estrogen-mediated stabilization of vitellogenin mRNA. Vigilin is up-regulated by cholesterol loading of cells and functions to protect cells from over-accumulation of cholesterol. It may play a role in cell sterol metabolism. Disruption of human vigilin impairs chromosome condensation and segregation. Vigilin has a unique structure of 14-15 consecutively arranged, but non-identical K-homology (KH) domains which apparently mediate RNA-protein binding. The model corresponds to the tenth one.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*....
gi 255725734 318 LIGKQGARINGVRKITGATISI-SDGGEDERIFTITGSSQAVEKAKQMI 365
Cdd:cd22413   17 LIGRGGANIRKIRDNTGARIIFpTARDEDQELITIIGTKEAVEKAKEEL 65

K homology RNA-binding domain;

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 255725734    99 INYRVLVSAKEAGCLIGTNGQVIDSIRGETNTKAGISRlvPGSHERILTVSGKLDDCAKALSYFAQAL 166
Cdd:smart00322   3 VTIEVLIPADKVGLIIGKGGSTIKKIEEETGVKIDIPG--PGSEERVVEITGPPENVEKAAELILEIL 68

type I K homology (KH) RNA-binding domain found in polyribonucleotide nucleotidyltransferase (PNPase) and similar proteins; PNPase, also called polynucleotide phosphorylase, is a polyribonucleotide nucleotidyl transferase that degrades mRNA in prokaryotes and plant chloroplasts. It catalyzes the phosphorolysis of single-stranded polyribonucleotides processively in the 3'- to 5'-direction. It is also involved, along with RNase II, in tRNA processing. The C-terminal region of PNPase contains domains homologous to those in other RNA binding proteins: a KH domain and an S1 domain. The model corresponds to the KH domain.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 255725734 304 KKATLTFPNDIVGALIGKQGARINGVRKITGATISISDGGEderiFTITGSSQ-AVEKAKQMIyQNYKREEE 374
Cdd:cd02393    4 RITTIKIPPDKIGDVIGPGGKTIRAIIEETGAKIDIEDDGT----VTIFATDKeSAEAAKAMI-EDIVAEPE 70

type I K homology (KH) RNA-binding domain found in Drosophila melanogaster eukaryotic translation initiation factor 4E-binding protein Mextli and similar proteins; Mextli is a novel eukaryotic translation initiation factor 4E-binding protein that promotes translation in Drosophila melanogaster.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*..
gi 255725734 311 PNDIVGALIGKQGARINGVRKITGATISIS--DGGEDERIFTITGSSQAVEKAKQMI 365
Cdd:cd22454   11 PNADVGKVIGKGGETIKRIEALTDTVITFErvNGGSPNREVQITGSPDNVAAAKRLI 67

K homology (KH) RNA-binding domain, type I; KH binds single-stranded RNA or DNA. It is found in a wide variety of proteins including ribosomal proteins, transcription factors and post-transcriptional modifiers of mRNA. There are two different KH domains that belong to different protein folds, but they share a single KH motif. The KH motif is folded into a beta alpha alpha beta unit. In addition to the core, type II KH domains (e.g. ribosomal protein S3) include an N-terminal extension and type I KH domains (e.g. hnRNP K) contain a C-terminal extension. Some KH-I superfamily members contain a divergent KH domain that lacks the RNA-binding GXXG motif. Some others have a mutated GXXG motif which may or may not have nucleic acid binding ability.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*..
gi 255725734 102 RVLVSAKEAGCLIGTNGQVIDSIRGETNTKAGISRLVPGSHERILTVSGKLDDCAKA 158
Cdd:cd00105    2 EIEVPSELVGLIIGKGGSTIKEIEEETGARIQIPKEGEGSGERVVTITGTPEAVEKA 58

second type I K homology (KH) RNA-binding domain found in Arabidopsis thaliana RNA-binding KH domain-containing protein PEPPER and similar proteins; The family includes a group of plant RNA-binding KH domain-containing proteins, such as PEPPER, flowering locus K homology domain protein (FLK), RNA-binding KH domain-containing protein RCF3 and KH domain-containing protein HEN4. PEPPER regulates vegetative and gynoecium development. It acts as a positive regulator of the central floral repressor FLOWERING LOCUS C. In concert with HUA2, PEPPER antagonizes FLK by positively regulating FLC probably at transcriptional and post-transcriptional levels, and thus acts as a negative regulator of flowering. FLK, also called flowering locus KH domain protein, regulates positively flowering by repressing FLC expression and post-transcriptional modification. PEPPER and FLK contain three K-homology (KH) RNA-binding domains. RCF3, also called protein ENHANCED STRESS RESPONSE 1 (ESR1), or protein HIGH OSMOTIC STRESS GENE EXPRESSION 5 (HOS5), or protein REGULATOR OF CBF GENE EXPRESSION 3, or protein SHINY 1 (SHI1), acts as negative regulator of osmotic stress-induced gene expression. It is involved in the regulation of thermotolerance responses under heat stress. It functions as an upstream regulator of heat stress transcription factor (HSF) genes. HEN4, also called protein HUA ENHANCER 4, plays a role in floral reproductive organ identity in the third whorl and floral determinacy specification by specifically promoting the processing of AGAMOUS (AG) pre-mRNA. It functions in association with HUA1 and HUA2. RCF3 and HEN4 contain five KH RNA-binding domains. The model corresponds to the KH2 domain of PEPPER and FLK, as well as KH2 and KH4 domains of RCF3 and HEN4.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 255725734 193 ILRLLIPNTQMGTLIGSKGARIQQIQ--SKYNISMIASKSFLPG--SNERLVELQGSVDDLYDSLRVISRCL 260
Cdd:cd22460    1 SARLLVASSQAGSLIGKGGAIIKQIReeSGASVRILPEEELPPCasPDDRVVQISGEAQAVKKALELVSSRL 72

second type I K homology (KH) RNA-binding domain found in heterogeneous nuclear ribonucleoprotein K (hnRNP K) and similar proteins; hnRNP K, also called transformation up-regulated nuclear protein (TUNP), is a pre-mRNA binding protein that binds tenaciously to poly(C) sequences. It may be involved in the nuclear metabolism of hnRNAs, particularly for pre-mRNAs that contain cytidine-rich sequences. It can also bind poly(C) single-stranded DNA. hnRNP K plays an important role in p53/TP53 response to DNA damage, acting at the level of both transcription activation and repression. hnRNP K contains three K-homology (KH) RNA-binding domains. The model corresponds to the second one.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*....
gi 255725734 102 RVLVSAKEAGCLIGTNGQVIDSIRGETNTKAGI-SRLVPGSHERILTVSGKLDDCAKAL 159
Cdd:cd22433    5 RLLVHQSQAGCIIGRAGFKIKELREKTGATIKVySECCPRSTDRVVQIGGKPDKVVECI 63

second type I K homology (KH) RNA-binding domain found in the insulin-like growth factor 2 mRNA-binding protein (IGF2BP) family; The IGF2BP family includes three members: IGF2BP1/IMP-1/ CRD-BP/ VICKZ1, IGF2BP2/IMP-2/ VICKZ2, and IGF2BP3/IMP-3/VICKZ3, which are RNA-binding factors that recruit target transcripts to cytoplasmic protein-RNA complexes (mRNPs). They function by binding to the 5' UTR of the insulin-like growth factor 2 (IGF2) mRNA and regulating IGF2 translation. IGF2BP proteins contain four K-homology (KH) RNA-binding domains which are important in RNA binding and are known to be involved in RNA synthesis and metabolism. The model corresponds to the second one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 255725734 311 PNDIVGALIGKQGARINGVRKITGATISISDGGED-----ERIFTITGSSQAVEKAKQMI 365
Cdd:cd22401    7 HNNLCGRLIGKDGRNIKKIMEDTNTKITISSLQDLtsynpERTITIKGSLEAMSEAESLI 66

second type I K homology (KH) RNA-binding domain found in Arabidopsis thaliana RNA-binding KH domain-containing protein PEPPER and similar proteins; The family includes a group of plant RNA-binding KH domain-containing proteins, such as PEPPER, flowering locus K homology domain protein (FLK), RNA-binding KH domain-containing protein RCF3 and KH domain-containing protein HEN4. PEPPER regulates vegetative and gynoecium development. It acts as a positive regulator of the central floral repressor FLOWERING LOCUS C. In concert with HUA2, PEPPER antagonizes FLK by positively regulating FLC probably at transcriptional and post-transcriptional levels, and thus acts as a negative regulator of flowering. FLK, also called flowering locus KH domain protein, regulates positively flowering by repressing FLC expression and post-transcriptional modification. PEPPER and FLK contain three K-homology (KH) RNA-binding domains. RCF3, also called protein ENHANCED STRESS RESPONSE 1 (ESR1), or protein HIGH OSMOTIC STRESS GENE EXPRESSION 5 (HOS5), or protein REGULATOR OF CBF GENE EXPRESSION 3, or protein SHINY 1 (SHI1), acts as negative regulator of osmotic stress-induced gene expression. It is involved in the regulation of thermotolerance responses under heat stress. It functions as an upstream regulator of heat stress transcription factor (HSF) genes. HEN4, also called protein HUA ENHANCER 4, plays a role in floral reproductive organ identity in the third whorl and floral determinacy specification by specifically promoting the processing of AGAMOUS (AG) pre-mRNA. It functions in association with HUA1 and HUA2. RCF3 and HEN4 contain five KH RNA-binding domains. The model corresponds to the KH2 domain of PEPPER and FLK, as well as KH2 and KH4 domains of RCF3 and HEN4.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 255725734 102 RVLVSAKEAGCLIGTNGQVIDSIRGETNTKAGISR--LVPG---SHERILTVSGKLDDCAKAL 159
Cdd:cd22460    3 RLLVASSQAGSLIGKGGAIIKQIREESGASVRILPeeELPPcasPDDRVVQISGEAQAVKKAL 65

first type I K homology (KH) RNA-binding domain found in Arabidopsis thaliana protein BTR1 and similar proteins; BTR1, also called Binding to ToMV RNA 1, is a negative regulator of tomato mosaic virus (ToMV) multiplication but has no effect on the multiplication of cucumber mosaic virus (CMV). BTR1 contains three K-homology (KH) RNA-binding domains. The model corresponds to the first one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 255725734 192 TILRLLIPNTQMGTLIGSKGARIQQIQSKY--NISMIASKSFLPGSNERLVELQGSVDDLYDSLRVI 256
Cdd:cd22513    2 VVAKLLVSNAAAGSVIGKGGATINDFQAQSgaRIQLSRAQEFFPGTTDRVLLVSGSLNEVLTALNLI 68

second type I K homology (KH) RNA-binding domain found in poly(rC)-binding protein 3 (PCBP3) and similar proteins; PCBP3, also called alpha-CP3, or PCBP3-overlapping transcript, or PCBP3-overlapping transcript 1, or heterogeneous nuclear ribonucleoprotein E3, or hnRNP E3, is a single-stranded nucleic acid binding protein that binds preferentially to oligo dC. It can function as a repressor dependent on binding to single-strand and double-stranded poly(C) sequences. PCBP3 contains three K-homology (KH) RNA-binding domains. The model corresponds to the second one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 255725734 194 LRLLIPNTQMGTLIGSKGARIQQIQSKYNISMIASKSFLPGSNERLVELQGSVDDLYDSLRVISRCLME 262
Cdd:cd22519    8 LRLVVPASQCGSLIGKGGSKIKEIRESTGAQVQVAGDMLPNSTERAVTISGTPDAIIQCVKQICVVMLE 76

second type I K homology (KH) RNA-binding domain found in the insulin-like growth factor 2 mRNA-binding protein (IGF2BP) family; The IGF2BP family includes three members: IGF2BP1/IMP-1/ CRD-BP/ VICKZ1, IGF2BP2/IMP-2/ VICKZ2, and IGF2BP3/IMP-3/VICKZ3, which are RNA-binding factors that recruit target transcripts to cytoplasmic protein-RNA complexes (mRNPs). They function by binding to the 5' UTR of the insulin-like growth factor 2 (IGF2) mRNA and regulating IGF2 translation. IGF2BP proteins contain four K-homology (KH) RNA-binding domains which are important in RNA binding and are known to be involved in RNA synthesis and metabolism. The model corresponds to the second one.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 255725734 111 GCLIGTNGQVIDSIRGETNTKAGISR---LVPGSHERILTVSGKLDDCAKA 158
Cdd:cd22401   12 GRLIGKDGRNIKKIMEDTNTKITISSlqdLTSYNPERTITIKGSLEAMSEA 62

eighth type I K homology (KH) RNA-binding domain found in vigilin and similar proteins; Vigilin, also called high density lipoprotein-binding protein, or HDL-binding protein, is a ubiquitous and highly conserved RNA-binding protein that shuttles between nucleus and cytoplasm presumably in contact with RNA molecules. It may be involved in chromosome partitioning at mitosis, facilitating translation and tRNA transport, and control of mRNA metabolism, including estrogen-mediated stabilization of vitellogenin mRNA. Vigilin is up-regulated by cholesterol loading of cells and functions to protect cells from over-accumulation of cholesterol. It may play a role in cell sterol metabolism. Disruption of human vigilin impairs chromosome condensation and segregation. Vigilin has a unique structure of 14-15 consecutively arranged, but non-identical K-homology (KH) domains which apparently mediate RNA-protein binding. The model corresponds to the eighth one.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 255725734 315 VGALIGKQGARINGVRKITGATISISDGGEDERIFTITGSSQAVEKAKQMI 365
Cdd:cd22411   11 HKNIIGKGGATIKKIREETNTRIDLPEENSDSDVITITGKKEDVEKARERI 61

second type I K homology (KH) RNA-binding domain found in a family of fragile X mental retardation protein (FMR1) and fragile X related (FXR) proteins; The FMR1/FXR family includes FMR1 (also known as FMRP) and its two homologues, fragile X related 1 (FXR1) and 2 (FXR2). They are involved in translational regulation, particularly in neuronal cells and play an important role in the regulation of glutamate-mediated neuronal activity and plasticity. Each of these three proteins can form heteromers with the others, and each can also form homomers. Lack of expression of FMR1 results in mental retardation and macroorchidism. FXR1 and FXR2 may play important roles in the function of FMR1 and in the pathogenesis of the Fragile X Mental Retardation Syndrome. Members of this family contain three K-homology (KH) RNA-binding domains. The model corresponds to the second one.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*...
gi 255725734 309 TFPNDIVGALIGKQGARINGVRKITGaTISIsDGGEDERIFTITGSS-QAVEKAKQMI 365
Cdd:cd22426    7 KVDPDLIGLAIGSHGSNIQQARKIPG-VESI-DVDEEDGTFRIYGETpEAVEKARALL 62

first type I K homology (KH) RNA-binding domain found in heterogeneous nuclear ribonucleoprotein K (hnRNP K) and similar proteins; hnRNP K, also called transformation up-regulated nuclear protein (TUNP), is a pre-mRNA binding protein that binds tenaciously to poly(C) sequences. It may be involved in the nuclear metabolism of hnRNAs, particularly for pre-mRNAs that contain cytidine-rich sequences. It can also bind poly(C) single-stranded DNA. hnRNP K plays an important role in p53/TP53 response to DNA damage, acting at the level of both transcription activation and repression. hnRNP K contains three K-homology (KH) RNA-binding domains. The model corresponds to the first one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 255725734  99 INYRVLVSAKEAGCLIGTNGQVIDSIRGETNtkAGISrlVPGSH--ERILTVSGKLDDCAKALS 160
Cdd:cd22432    2 VELRLLIPSKAAGAIIGKGGENIKRLRTEYN--ASVS--VPDSSgpERILTISADRETVLGILT 61

second type I K homology (KH) RNA-binding domain found in poly(rC)-binding protein 1 (PCBP1) and similar proteins; The family includes PCBP1 (also called alpha-CP1, or heterogeneous nuclear ribonucleoprotein E1, or hnRNP E1, or nucleic acid-binding protein SUB2.3) and PCBP2 (also called alpha-CP2, or heterogeneous nuclear ribonucleoprotein E2, or hnRNP E2). They are single-stranded nucleic acid binding proteins that bind preferentially to oligo dC. They act as iron chaperones for ferritin. In case of infection by poliovirus, PCBP1 plays a role in initiation of viral RNA replication in concert with the viral protein 3CD. PCBP2 is a major cellular poly(rC)-binding protein. It also binds poly(rU). PCBP2 negatively regulates cellular antiviral responses mediated by MAVS signaling. It acts as an adapter between MAVS and the E3 ubiquitin ligase ITCH, therefore triggering MAVS ubiquitination and degradation. PCBP2 forms a metabolon with the heme oxygenase 1/cytochrome P450 reductase complex for heme catabolism and iron transfer. Both PCBP1 and PCBP2 contain three K-homology (KH) RNA-binding domains. The model corresponds to the second one.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 255725734 194 LRLLIPNTQMGTLIGSKGARIQQIQSKYNISMIASKSFLPGSNERLVELQGSVDDLYDSLRVISRCLME 262
Cdd:cd22518    9 LRLVVPASQCGSLIGKGGCKIKEIRESTGAQVQVAGDMLPNSTERAITIAGIPQSIIECVKQICVVMLE 77