Nuclear transport factor 2 (NTF2) domain plays an important role in the trafficking of macromolecules, ions and small molecules between the cytoplasm and nucleus. This bi-directional transport of macromolecules across the nuclear envelope requires many soluble factors that includes GDP-binding protein Ran (RanGDP). RanGDP is required for both import and export of proteins and poly(A) RNA. RanGDP also has been implicated in cell cycle control, specifically in mitotic spindle assembly. In interphase cells, RanGDP is predominately nuclear and thought to be GTP bound, but it is also present in the cytoplasm, probably in the GDP-bound state. NTF2 mediates the nuclear import of RanGDP. NTF2 binds to both RanGDP and FxFG repeat-containing nucleoporins.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 955337014  13 SAQVVGNAFVEQYYHILHHSPGSVYRFYQDSSVISRPDssgvMTSVTTMKGINEKILSLNFKEFKAEIKTADAQKSYKEG 92
Cdd:cd00780    1 SAEDVAKAFVQQYYSIFDNNREGLHRLYGDTSMLSREG----MKQVTGRDAIVEKLSSLPFQKTKHKITTVDSQPTPSGG 76

                         90       100       110       120
                 ....*....|....*....|....*....|....*....|...
gi 955337014  93 VTVLVTGCLTGKDNLRRKFAQSFFLAPQDNGYFVLNDVFRYVE 135
Cdd:cd00780   77 VIVMVTGSLKLDEQPPRKFSQTFVLAPQNGGYFVLNDIFRFVD 119

Nuclear transport factor 2 (NTF2) domain plays an important role in the trafficking of macromolecules, ions and small molecules between the cytoplasm and nucleus. This bi-directional transport of macromolecules across the nuclear envelope requires many soluble factors that includes GDP-binding protein Ran (RanGDP). RanGDP is required for both import and export of proteins and poly(A) RNA. RanGDP also has been implicated in cell cycle control, specifically in mitotic spindle assembly. In interphase cells, RanGDP is predominately nuclear and thought to be GTP bound, but it is also present in the cytoplasm, probably in the GDP-bound state. NTF2 mediates the nuclear import of RanGDP. NTF2 binds to both RanGDP and FxFG repeat-containing nucleoporins.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 955337014  13 SAQVVGNAFVEQYYHILHHSPGSVYRFYQDSSVISRPDssgvMTSVTTMKGINEKILSLNFKEFKAEIKTADAQKSYKEG 92
Cdd:cd00780    1 SAEDVAKAFVQQYYSIFDNNREGLHRLYGDTSMLSREG----MKQVTGRDAIVEKLSSLPFQKTKHKITTVDSQPTPSGG 76

                         90       100       110       120
                 ....*....|....*....|....*....|....*....|...
gi 955337014  93 VTVLVTGCLTGKDNLRRKFAQSFFLAPQDNGYFVLNDVFRYVE 135
Cdd:cd00780   77 VIVMVTGSLKLDEQPPRKFSQTFVLAPQNGGYFVLNDIFRFVD 119

RNA recognition motif;

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 955337014   304 SIYIRNLPLNVTVAQLELEFKKFGPIKpgGIQVRNNKQQGYC--FGFVEFLSLNSMNSAIQA-SPVPIGGRQAVV 375
Cdd:smart00360   1 TLFVGNLPPDTTEEELRELFSKFGKVE--SVRLVRDKETGKSkgFAFVEFESEEDAEKALEAlNGKELDGRPLKV 73

RNA recognition motif (RRM) superfamily; RRM, also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), is a highly abundant domain in eukaryotes found in proteins involved in post-transcriptional gene expression processes including mRNA and rRNA processing, RNA export, and RNA stability. This domain is 90 amino acids in length and consists of a four-stranded beta-sheet packed against two alpha-helices. RRM usually interacts with ssRNA, but is also known to interact with ssDNA as well as proteins. RRM binds a variable number of nucleotides, ranging from two to eight. The active site includes three aromatic side-chains located within the conserved RNP1 and RNP2 motifs of the domain. The RRM domain is found in a variety heterogeneous nuclear ribonucleoproteins (hnRNPs), proteins implicated in regulation of alternative splicing, and protein components of small nuclear ribonucleoproteins (snRNPs).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIKpgGIQV-RNNKQQGYCFGFVEFLSLNSMNSAIQA-SPVPIGGRQAVVE 376
Cdd:cd00590    1 LFVGNLPPDTTEEDLRELFSKFGEVV--SVRIvRDRDGKSKGFAFVEFESPEDAEKALEAlNGTELGGRPLKVS 72

polyadenylate binding protein, human types 1, 2, 3, 4 family; These eukaryotic proteins recognize the poly-A of mRNA and consists of four tandem RNA recognition domains at the N-terminus (rrm: pfam00076) followed by a PABP-specific domain (pfam00658) at the C-terminus. The protein is involved in the transport of mRNA's from the nucleus to the cytoplasm. There are four paralogs in Homo sapiens which are expressed in testis, platelets, broadly expressed and of unknown tissue range.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 955337014  301 EGHSIYIRNLPLNVTVAQLELEFKKFGPIKPGGIqVRNNKQQGYCFGFVEFLSLNSMNSAIQ 362
Cdd:TIGR01628 284 QGVNLYVKNLDDTVTDEKLRELFSECGEITSAKV-MLDEKGVSRGFGFVCFSNPEEANRAVT 344

Nuclear transport factor 2 (NTF2) domain plays an important role in the trafficking of macromolecules, ions and small molecules between the cytoplasm and nucleus. This bi-directional transport of macromolecules across the nuclear envelope requires many soluble factors that includes GDP-binding protein Ran (RanGDP). RanGDP is required for both import and export of proteins and poly(A) RNA. RanGDP also has been implicated in cell cycle control, specifically in mitotic spindle assembly. In interphase cells, RanGDP is predominately nuclear and thought to be GTP bound, but it is also present in the cytoplasm, probably in the GDP-bound state. NTF2 mediates the nuclear import of RanGDP. NTF2 binds to both RanGDP and FxFG repeat-containing nucleoporins.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 955337014  13 SAQVVGNAFVEQYYHILHHSPGSVYRFYQDSSVISRPDssgvMTSVTTMKGINEKILSLNFKEFKAEIKTADAQKSYKEG 92
Cdd:cd00780    1 SAEDVAKAFVQQYYSIFDNNREGLHRLYGDTSMLSREG----MKQVTGRDAIVEKLSSLPFQKTKHKITTVDSQPTPSGG 76

                         90       100       110       120
                 ....*....|....*....|....*....|....*....|...
gi 955337014  93 VTVLVTGCLTGKDNLRRKFAQSFFLAPQDNGYFVLNDVFRYVE 135
Cdd:cd00780   77 VIVMVTGSLKLDEQPPRKFSQTFVLAPQNGGYFVLNDIFRFVD 119

Nuclear transport factor 2 (NTF2-like) superfamily. This family includes members of the NTF2 family, Delta-5-3-ketosteroid isomerases, Scytalone Dehydratases, and the beta subunit of Ring hydroxylating dioxygenases. This family is a classic example of divergent evolution wherein the proteins have many common structural details but diverge greatly in their function. For example, nuclear transport factor 2 (NTF2) mediates the nuclear import of RanGDP and binds to both RanGDP and FxFG repeat-containing nucleoporins while Ketosteroid isomerases catalyze the isomerization of delta-5-3-ketosteroid to delta-4-3-ketosteroid, by intramolecular transfer of the C4-beta proton to the C6-beta position. While the function of the beta sub-unit of the Ring hydroxylating dioxygenases is not known, Scytalone Dehydratases catalyzes two reactions in the biosynthetic pathway that produces fungal melanin. Members of the NTF2-like superfamily are widely distributed among bacteria, archaea and eukaryotes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 955337014  20 AFVEQYYHILH-HSPGSVYRFYQDSSVISRPDSSGVMTSVTTMKGINEKILSLNFKEFKAE--IKTADAQKSY-KEGVTV 95
Cdd:cd00531    3 QFLYRYARLLDaGDREWLALLYADDAYFEPPGGDGLIYPDDGREAIEDRVRRLPFGPSRTRhlVSNVDVQPGDdGEGVVV 82

                         90       100       110       120
                 ....*....|....*....|....*....|....*....|..
gi 955337014  96 LVTGCLTGKDNLR---RKFAQSFFLAPQDNGYFVLNDVFRYV 134
Cdd:cd00531   83 SVFGVLRTRGDGEqdvFAGGQTFVLRPQGGGGKIANRRFRLD 124

RNA recognition motif. (a.k.a. RRM, RBD, or RNP domain); The RRM motif is probably diagnostic of an RNA binding protein. RRMs are found in a variety of RNA binding proteins, including various hnRNP proteins, proteins implicated in regulation of alternative splicing, and protein components of snRNPs. The motif also appears in a few single stranded DNA binding proteins. The RRM structure consists of four strands and two helices arranged in an alpha/beta sandwich, with a third helix present during RNA binding in some cases The C-terminal beta strand (4th strand) and final helix are hard to align and have been omitted in the SEED alignment The LA proteins have an N terminal rrm which is included in the seed. There is a second region towards the C terminus that has some features characteriztic of a rrm but does not appear to have the important structural core of a rrm. The LA proteins are one of the main autoantigens in Systemic lupus erythematosus (SLE), an autoimmune disease.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|
gi 955337014  305 IYIRNLPLNVTVAQLELEFKKFGPIKpgGIQV-RNNKQQGYCFGFVEFLSLNSMNSAIQA 363
Cdd:pfam00076   1 LFVGNLPPDTTEEDLKDLFSKFGPIK--SIRLvRDETGRSKGFAFVEFEDEEDAEKAIEA 58

RNA recognition motif (RRM) domain [Translation, ribosomal structure and biogenesis];

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 955337014 304 SIYIRNLPLNVTVAQLELEFKKFGPIKpgGIQVRNNKQQGYC--FGFVEFLSLNSMNSAIQA-SPVPIGGRQAVVEIKR 379
Cdd:COG0724    3 KIYVGNLPYSVTEEDLRELFSEYGEVT--SVKLITDRETGRSrgFGFVEMPDDEEAQAAIEAlNGAELMGRTLKVNEAR 79

RNA recognition motif 3 in fungal pre-messenger RNA splicing protein 24 (Prp24) and similar proteins; This subfamily corresponds to the RRM3 of Prp24, also termed U4/U6 snRNA-associated-splicing factor PRP24 (U4/U6 snRNP), an RNA-binding protein with four well conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). It facilitates U6 RNA base-pairing with U4 RNA during spliceosome assembly. Prp24 specifically binds free U6 RNA primarily with RRMs 1 and 2 and facilitates pairing of U6 RNA bases with U4 RNA bases. Additionally, it may also be involved in dissociation of the U4/U6 complex during spliceosome activation.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIKPGGIQVRNNKQQGY---CFGFVEFLSLNSMNSAIQASPVPIGGR 371
Cdd:cd12298    3 IRVRNLDFELDEEALRGIFEKFGEIESINIPKKQKNRKGRhnnGFAFVTFEDADSAESALQLNGTLLDNR 72

RNA recognition motif (RRM) found in U1 small nuclear ribonucleoprotein 70 kDa (U1-70K) and similar proteins; This subfamily corresponds to the RRM of U1-70K, also termed snRNP70, a key component of the U1 snRNP complex, which is one of the key factors facilitating the splicing of pre-mRNA via interaction at the 5' splice site, and is involved in regulation of polyadenylation of some viral and cellular genes, enhancing or inhibiting efficient poly(A) site usage. U1-70K plays an essential role in targeting the U1 snRNP to the 5' splice site through protein-protein interactions with regulatory RNA-binding splicing factors, such as the RS protein ASF/SF2. Moreover, U1-70K protein can specifically bind to stem-loop I of the U1 small nuclear RNA (U1 snRNA) contained in the U1 snRNP complex. It also mediates the binding of U1C, another U1-specific protein, to the U1 snRNP complex. U1-70K contains a conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), followed by an adjacent glycine-rich region at the N-terminal half, and two serine/arginine-rich (SR) domains at the C-terminal half. The RRM is responsible for the binding of stem-loop I of U1 snRNA molecule. Additionally, the most prominent immunodominant region that can be recognized by auto-antibodies from autoimmune patients may be located within the RRM. The SR domains are involved in protein-protein interaction with SR proteins that mediate 5' splice site recognition. For instance, the first SR domain is necessary and sufficient for ASF/SF2 Binding. The family also includes Drosophila U1-70K that is an essential splicing factor required for viability in flies, but its SR domain is dispensable. The yeast U1-70k doesn't contain easily recognizable SR domains and shows low sequence similarity in the RRM region with other U1-70k proteins and therefore not included in this family. The RRM domain is dispensable for yeast U1-70K function.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 955337014 314 VTVAQLELEFKKFGPIKPGGIqVRN---NKQQGYcfGFVEFLSLNSMNSAIQ-ASPVPIGGRQAVVEIKRTTT 382
Cdd:cd12236   13 TTESKLRREFEKYGPIKRVRL-VRDkktGKSRGY--AFIEFEHERDMKAAYKhADGKKIDGRRVLVDVERGRT 82

RNA recognition motif (RRM) found in Tudor domain-containing protein 10 (TDRD10) and similar proteins; TDRD10 is widely expressed and localized both to the nucleus and cytoplasm and may play general roles like regulation of RNA metabolism. It contains a Tudor domain and a RNA recognition motif (RRM).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIKpggiqVRNNKQQGYCFGFVEFLSLNSMNSAIQA-SPVPIGGRQAVVE 376
Cdd:cd21617    2 VYVGNLPLDISEEEILQLFKAFNPVL-----VKKIRSGFKCFAFVDLGSDENVKLAIQQlNGTLFGGRRLVVN 69

RNA recognition motif (RRM) found in the scaffold attachment factor (SAFB) family; This subfamily corresponds to the RRM domain of the SAFB family, including scaffold attachment factor B1 (SAFB1), scaffold attachment factor B2 (SAFB2), SAFB-like transcriptional modulator (SLTM), and similar proteins, which are ubiquitously expressed. SAFB1, SAFB2 and SLTM have been implicated in many diverse cellular processes including cell growth and transformation, stress response, and apoptosis. They share high sequence similarities and all contain a scaffold attachment factor-box (SAF-box, also known as SAP domain) DNA-binding motif, an RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a region rich in glutamine and arginine residues. SAFB1 is a nuclear protein with a distribution similar to that of SLTM, but unlike that of SAFB2, which is also found in the cytoplasm. To a large extent, SAFB1 and SLTM might share similar functions, such as the inhibition of an oestrogen reporter gene. The additional cytoplasmic localization of SAFB2 implies that it could play additional roles in the cytoplasmic compartment which are distinct from the nuclear functions shared with SAFB1 and SLTM.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 955337014 304 SIYIRNLPLNVTVAQLELEFKKFGpiKPGGIQVRNNKQQGY--CFGFVEFLSLNSMNSAIQA-SPVPIGGRQAVVE 376
Cdd:cd12417    1 NLWISGLSDTTKAADLKKIFSKYG--KVVSAKVVTSARTPGsrCYGYVTMASVEEADLCIKSlNKTELHGRVITVE 74

RNA recognition motif 2 (RRM2) found in CUGBP Elav-like family member CELF-3, CELF-4, CELF-5, CELF-6 and similar proteins; This subgroup corresponds to the RRM3 of CELF-3, CELF-4, CELF-5, and CELF-6, all of which belong to the CUGBP1 and ETR-3-like factors (CELF) or BRUNOL (Bruno-like) family of RNA-binding proteins that display dual nuclear and cytoplasmic localizations and have been implicated in the regulation of pre-mRNA splicing and in the control of mRNA translation and deadenylation. CELF-3, expressed in brain and testis only, is also known as bruno-like protein 1 (BRUNOL-1), or CAG repeat protein 4, or CUG-BP- and ETR-3-like factor 3, or embryonic lethal abnormal vision (ELAV)-type RNA-binding protein 1 (ETR-1), or expanded repeat domain protein CAG/CTG 4, or trinucleotide repeat-containing gene 4 protein (TNRC4). It plays an important role in the pathogenesis of tauopathies. CELF-3 contains three highly conserved RNA recognition motifs (RRMs), also known as RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains): two consecutive RRMs (RRM1 and RRM2) situated in the N-terminal region followed by a linker region and the third RRM (RRM3) close to the C-terminus of the protein.The effect of CELF-3 on tau splicing is mediated mainly by the RNA-binding activity of RRM2. The divergent linker region might mediate the interaction of CELF-3 with other proteins regulating its activity or involved in target recognition. CELF-4, highly expressed throughout the brain and in glandular tissues, moderately expressed in heart, skeletal muscle, and liver, is also known as bruno-like protein 4 (BRUNOL-4), or CUG-BP- and ETR-3-like factor 4. Like CELF-3, CELF-4 also contains three highly conserved RRMs. The splicing activation or repression activity of CELF-4 on some specific substrates is mediated by its RRM1/RRM2. Both, RRM1 and RRM2 of CELF-4, can activate cardiac troponin T (cTNT) exon 5 inclusion. CELF-5, expressed in brain, is also known as bruno-like protein 5 (BRUNOL-5), or CUG-BP- and ETR-3-like factor 5. Although its biological role remains unclear, CELF-5 shares same domain architecture with CELF-3. CELF-6, strongly expressed in kidney, brain, and testis, is also known as bruno-like protein 6 (BRUNOL-6), or CUG-BP- and ETR-3-like factor 6. It activates exon inclusion of a cardiac troponin T minigene in transient transfection assays in an muscle-specific splicing enhancer (MSE)-dependent manner and can activate inclusion via multiple copies of a single element, MSE2. CELF-6 also promotes skipping of exon 11 of insulin receptor, a known target of CELF activity that is expressed in kidney. In addition to three highly conserved RRMs, CELF-6 also possesses numerous potential phosphorylation sites, a potential nuclear localization signal (NLS) at the C terminus, and an alanine-rich region within the divergent linker region.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 955337014 301 EGHSIYIRNLPLNVTVAQLELEFKKFGPIKPGGIQVRNNKQQGYCFGFVEFLSLNSMNSAIQA 363
Cdd:cd12639    3 EGCNLFIYHLPQEFGDAELMQMFLPFGNVISAKVFVDRATNQSKCFGFVSFDNPASAQAAIQA 65

RNA recognition motif 3 (RRM3) found in RNA-binding protein 28 (RBM28) and similar proteins; This subfamily corresponds to the RRM3 of RBM28 and Nop4p. RBM28 is a specific nucleolar component of the spliceosomal small nuclear ribonucleoproteins (snRNPs), possibly coordinating their transition through the nucleolus. It specifically associates with U1, U2, U4, U5, and U6 small nuclear RNAs (snRNAs), and may play a role in the maturation of both small nuclear and ribosomal RNAs. RBM28 has four RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and an extremely acidic region between RRM2 and RRM3. The family also includes nucleolar protein 4 (Nop4p or Nop77p) encoded by YPL043W from Saccharomyces cerevisiae. It is an essential nucleolar protein involved in processing and maturation of 27S pre-rRNA and biogenesis of 60S ribosomal subunits. Nop4p also contains four RRMs.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 955337014 303 HSIYIRNLPLNVTVAQLELEFKKFGPIKPGGIQVrnNKQQGYCFG--FVEFLSLNSMNSAIQASP-------VPIGGRQ 372
Cdd:cd12415    1 KTVFIRNLSFDTTEEDLKEFFSKFGEVKYARIVL--DKDTGHSKGtaFVQFKTKESADKCIEAANdesedggLVLDGRK 77

RNA recognition motif 1 (RRM1) found in heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) and similar proteins; This subgroup corresponds to the RRM1 of hnRNP A1, also termed helix-destabilizing protein, or single-strand RNA-binding protein, or hnRNP core protein A1, and is an abundant eukaryotic nuclear RNA-binding protein that may modulate splice site selection in pre-mRNA splicing. hnRNP A1 has been characterized as a splicing silencer, often acting in opposition to an activating hnRNP H. It silences exons when bound to exonic elements in the alternatively spliced transcripts of c-src, HIV, GRIN1, and beta-tropomyosin. hnRNP A1 can shuttle between the nucleus and the cytoplasm. Thus, it may be involved in transport of cellular RNAs, including the packaging of pre-mRNA into hnRNP particles and transport of poly A+ mRNA from the nucleus to the cytoplasm. The cytoplasmic hnRNP A1 has high affinity with AU-rich elements, whereas the nuclear hnRNP A1 has high affinity with a polypyrimidine stretch bordered by AG at the 3' ends of introns. hnRNP A1 is also involved in the replication of an RNA virus, such as mouse hepatitis virus (MHV), through an interaction with the transcription-regulatory region of viral RNA. hnRNP A1, together with the scaffold protein septin 6, serves as host protein to form a complex with NS5b and viral RNA, and further plays important roles in the replication of Hepatitis C virus (HCV). hnRNP A1 contains two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), followed by a long glycine-rich region at the C-terminus. The RRMs of hnRNP A1 play an important role in silencing the exon and the glycine-rich domain is responsible for protein-protein interactions.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIKPGGIQVRNNKQQGYCFGFVEFLSLNSMNSAIQASPVPIGGRqaVVEIKRTTTR 383
Cdd:cd12761    5 LFIGGLSFETTDESLRSHFEQWGTLTDCVVMRDPNTKRSRGFGFVTYATVEEVDAAMNARPHKVDGR--VVEPKRAVSR 81

RNA recognition motif 1 (RRM1) found in vertebrate RNA-binding protein 26 (RBM26) and similar proteins; This subfamily corresponds to the RRM1 of RBM26, and the RRM of RBM27. RBM26, also known as cutaneous T-cell lymphoma (CTCL) tumor antigen se70-2, represents a cutaneous lymphoma (CL)-associated antigen. It contains two RNA recognition motifs (RRMs), also known as RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). The RRMs may play some functional roles in RNA-binding or protein-protein interactions. RBM27 contains only one RRM; its biological function remains unclear.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 955337014 304 SIYIRNLPL-NVTVAQLELEFKKFGPIKpgGIQVRNNKQQgycfGFVEFLSLNSMNSAIQaSPVPI 368
Cdd:cd12257    3 TLEVRNIPPeLNNITKLREHFSKFGTIV--NIQVNYNPES----ALVQFSTSEEANKAYR-SPEAV 61

RNA recognition motif (RRM) found in serine/arginine-rich splicing factor 3 (SRSF3) and similar proteins; This subfamily corresponds to the RRM of two serine/arginine (SR) proteins, serine/arginine-rich splicing factor 3 (SRSF3) and serine/arginine-rich splicing factor 7 (SRSF7). SRSF3, also termed pre-mRNA-splicing factor SRp20, modulates alternative splicing by interacting with RNA cis-elements in a concentration- and cell differentiation-dependent manner. It is also involved in termination of transcription, alternative RNA polyadenylation, RNA export, and protein translation. SRSF3 is critical for cell proliferation, and tumor induction and maintenance. It can shuttle between the nucleus and cytoplasm. SRSF7, also termed splicing factor 9G8, plays a crucial role in both constitutive splicing and alternative splicing of many pre-mRNAs. Its localization and functions are tightly regulated by phosphorylation. SRSF7 is predominantly present in the nuclear and can shuttle between nucleus and cytoplasm. It cooperates with the export protein, Tap/NXF1, helps mRNA export to the cytoplasm, and enhances the expression of unspliced mRNA. Moreover, SRSF7 inhibits tau E10 inclusion through directly interacting with the proximal downstream intron of E10, a clustering region for frontotemporal dementia with Parkinsonism (FTDP) mutations. Both SRSF3 and SRSF7 contain a single N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a C-terminal RS domain rich in serine-arginine dipeptides. The RRM domain is involved in RNA binding, and the RS domain has been implicated in protein shuttling and protein-protein interactions.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIK--------PGgiqvrnnkqqgycFGFVEF 351
Cdd:cd12373    2 VYVGNLGPRVTKRELEDAFEKYGPLRnvwvarnpPG-------------FAFVEF 43

RNA recognition motif 2 (RRM2) found in RNA-binding protein 34 (RBM34) and similar proteins; This subfamily corresponds to the RRM2 of RBM34, a putative RNA-binding protein containing two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). Although the function of RBM34 remains unclear currently, its RRM domains may participate in mRNA processing. RBM34 may act as an mRNA processing-related protein.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 955337014 304 SIYIRNLPLNVTVAQLELEFKKFGPIKPGGIqVRNNK-QQGYCFGFVEFLSLNSMNSAIQASPVPIGGRQ 372
Cdd:cd12395    1 SVFVGNLPFDIEEEELRKHFEDCGDVEAVRI-VRDREtGIGKGFGYVLFKDKDSVDLALKLNGSKLRGRK 69

polyadenylate binding protein, human types 1, 2, 3, 4 family; These eukaryotic proteins recognize the poly-A of mRNA and consists of four tandem RNA recognition domains at the N-terminus (rrm: pfam00076) followed by a PABP-specific domain (pfam00658) at the C-terminus. The protein is involved in the transport of mRNA's from the nucleus to the cytoplasm. There are four paralogs in Homo sapiens which are expressed in testis, platelets, broadly expressed and of unknown tissue range.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 955337014  301 EGHSIYIRNLPLNVTVAQLELEFKKFGPIKPGGIqVRNNKQQGYCFGFVEFLSLNSMNSAIQ 362
Cdd:TIGR01628 284 QGVNLYVKNLDDTVTDEKLRELFSECGEITSAKV-MLDEKGVSRGFGFVCFSNPEEANRAVT 344

RNA recognition motif 1 (RRM1) found in heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) and similar proteins; This subgroup corresponds to the RRM1 of hnRNP A2/B1 which is an RNA trafficking response element-binding protein that interacts with the hnRNP A2 response element (A2RE). Many mRNAs, such as myelin basic protein (MBP), myelin-associated oligodendrocytic basic protein (MOBP), carboxyanhydrase II (CAII), microtubule-associated protein tau, and amyloid precursor protein (APP) are trafficked by hnRNP A2/B1. hnRNP A2/B1 also functions as a splicing factor that regulates alternative splicing of the tumor suppressors, such as BIN1, WWOX, the antiapoptotic proteins c-FLIP and caspase-9B, the insulin receptor (IR), and the RON proto-oncogene among others. Moreover, the overexpression of hnRNP A2/B1 has been described in many cancers. It functions as a nuclear matrix protein involving in RNA synthesis and the regulation of cellular migration through alternatively splicing pre-mRNA. It may play a role in tumor cell differentiation. hnRNP A2/B1 contains two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), followed by a long glycine-rich region at the C-terminus.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIKPGGIQVRNNKQQGYCFGFVEFLSLNSMNSAIQASPVPIGGRqaVVEIKRTTTR 383
Cdd:cd12762    5 LFIGGLSFETTEESLRNYYEQWGKLTDCVVMRDPASKRSRGFGFVTFSSMAEVDAAMAARPHSIDGR--VVEPKRAVAR 81

RNA recognition motif (RRM) found in Saccharomyces cerevisiae nucleolar protein 6 (Nop6) and similar proteins; This subfamily corresponds to the RRM of Nop6, also known as Ydl213c, a component of 90S pre-ribosomal particles in yeast S. cerevisiae. It is enriched in the nucleolus and is required for 40S ribosomal subunit biogenesis. Nop6 is a non-essential putative RNA-binding protein with two N-terminal putative nuclear localisation sequences (NLS-1 and NLS-2) and an RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). It binds to the pre-rRNA early during transcription and plays an essential role in pre-rRNA processing.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIkpggIQVR------NNKQQGycFGFVEFLSLNSMNSAIQASPVPIGGRQAVVE 376
Cdd:cd12400    3 LFVGNLPYDTTAEDLKEHFKKAGEP----PSVRlltdkkTGKSKG--CAFVEFDNQKALQKALKLHHTSLGGRKINVE 74

RNA recognition motif 1 (RRM1) found in heterogeneous nuclear ribonucleoprotein L (hnRNP-L) and similar proteins; This subfamily corresponds to the RRM1 of heterogeneous nuclear ribonucleoprotein L (hnRNP-L), heterogeneous nuclear ribonucleoprotein L-like (hnRNP-LL), and similar proteins. hnRNP-L is a higher eukaryotic specific subunit of human KMT3a (also known as HYPB or hSet2) complex required for histone H3 Lys-36 trimethylation activity. It plays both, nuclear and cytoplasmic, roles in mRNA export of intronless genes, IRES-mediated translation, mRNA stability, and splicing. hnRNP-LL plays a critical and unique role in the signal-induced regulation of CD45 and acts as a global regulator of alternative splicing in activated T cells. It is closely related in domain structure and sequence to hnRNP-L, which contains three RNA-recognition motifs (RRMs), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIkpGGIQVRNNKQQgycfGFVEFLSLNSMNSAI---QASPVPIGGRQA 373
Cdd:cd12689    5 VHVRGLSEHVTEADLVEALQNFGPI--SYVTMMPKKRQ----ALVEFEDIEGAKACVnyaQQNPIYVGGRPA 70

RNA recognition motif 1 (RRM1) found in yeast nucleolar protein 3 (Npl3p) and similar proteins; This subfamily corresponds to the RRM1 of Npl3p, also termed mitochondrial targeting suppressor 1 protein, or nuclear polyadenylated RNA-binding protein 1. Npl3p is a major yeast RNA-binding protein that competes with 3'-end processing factors, such as Rna15, for binding to the nascent RNA, protecting the transcript from premature termination and coordinating transcription termination and the packaging of the fully processed transcript for export. It specifically recognizes a class of G/U-rich RNAs. Npl3p is a multi-domain protein containing two central RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), separated by a short linker and a C-terminal domain rich in glycine, arginine and serine residues.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*....
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIKPGGIQVRNNkqqgycFGFVEFlslNSMNSAIQA 363
Cdd:cd12340    2 LFVRPFPPDTSESAIREIFSPYGPVKEVKMLSDSN------FAFVEF---EELEDAIRA 51

RNA recognition motif 3 (RRM3) found in yeast nucleolar protein 4 (Nop4p) and similar proteins; This subgroup corresponds to the RRM3 of Nop4p (also known as Nop77p), encoded by YPL043W from Saccharomyces cerevisiae. It is an essential nucleolar protein involved in processing and maturation of 27S pre-rRNA and biogenesis of 60S ribosomal subunits. Nop4p has four RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 955337014 302 GHSIYIRNLPLNVTVAQLELEFKKFGPIKPGGIQVRNNKQQGYCFGFVEFLSLNSMNSAIQASP 365
Cdd:cd12676    1 GRTLFVRNLPFDATEDELYSHFSQFGPLKYARVVKDPATGRSKGTAFVKFKNKEDADNCLSAAP 64

RNA recognition motif 2 (RRM2) found in Schizosaccharomyces pombe mRNA export factor Crp79, meiotically up-regulated gene 28 protein (Mug28) and similar proteins; Crp79, also called meiotic expression up-regulated protein 5 (Mug5), or polyadenylate-binding protein crp79, or PABP, or poly(A)-binding protein, is an auxiliary mRNA export factor that binds the poly(A) tail of mRNA and is involved in the export of mRNA from the nucleus to the cytoplasm. Mug28 is a meiosis-specific protein that regulates spore wall formation. Members in this family contain three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). The model corresponds to the second RRM motif.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIKPGGI-QVRNNKqqGYCFGFVEFLSLNSMNSAIQA-SPVPIGGRQAVVEIK 378
Cdd:cd21621    1 LTVLNLPTDMTPKDLYNLFSEHGKVEGTAInQVPDNR--GRRYGEVAMNSYEDCQKALEYfNGYVYKGYILEVFYK 74

RNA recognition motif (RRM) found in cyclophilin-33 (Cyp33) and similar proteins; This subfamily corresponds to the RRM of Cyp33, also termed peptidyl-prolyl cis-trans isomerase E (PPIase E), or cyclophilin E, or rotamase E. Cyp33 is a nuclear RNA-binding cyclophilin with an N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a C-terminal PPIase domain. Cyp33 possesses RNA-binding activity and preferentially binds to polyribonucleotide polyA and polyU, but hardly to polyG and polyC. It binds specifically to mRNA, which can stimulate its PPIase activity. Moreover, Cyp33 interacts with the third plant homeodomain (PHD3) zinc finger cassette of the mixed lineage leukemia (MLL) proto-oncoprotein and a poly-A RNA sequence through its RRM domain. It further mediates downregulation of the expression of MLL target genes HOXC8, HOXA9, CDKN1B, and C-MYC, in a proline isomerase-dependent manner. Cyp33 also possesses a PPIase activity that catalyzes cis-trans isomerization of the peptide bond preceding a proline, which has been implicated in the stimulation of folding and conformational changes in folded and unfolded proteins. The PPIase activity can be inhibited by the immunosuppressive drug cyclosporin A.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*..
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIKPGGIQVRNNKQQGYCFGFVEF 351
Cdd:cd12347    1 LYVGGLAEEVDEKVLHAAFIPFGDIVDIQIPLDYETEKHRGFAFVEF 47

splicing factor, CC1-like family; This model represents a subfamily of RNA splicing factors including the Pad-1 protein (N. crassa), CAPER (M. musculus) and CC1.3 (H.sapiens). These proteins are characterized by an N-terminal arginine-rich, low complexity domain followed by three (or in the case of 4 H. sapiens paralogs, two) RNA recognition domains (rrm: pfam00706). These splicing factors are closely related to the U2AF splicing factor family (TIGR01642). A homologous gene from Plasmodium falciparum was identified in the course of the analysis of that genome at TIGR and was included in the seed.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 955337014  275 VESTEVPEAALESVSNPESSDAHEEVEGHSIYIRNLPLNVTVAQLELEFKKFGPIKPGGIQVRNNKQQGYCFGFVEFLSL 354
Cdd:TIGR01622 187 VQLSEAEKNRAARAATETSGHHPNSIPFHRLYVGNLHFNITEQDLRQIFEPFGEIEFVQLQKDPETGRSKGYGFIQFRDA 266

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|
gi 955337014  355 NSMNSA-IQASPVPIGGRqavveikrtTTRVGSGINGTGR 393
Cdd:TIGR01622 267 EQAKEAlEKMNGFELAGR---------PIKVGLGNDFTPE 297

RNA recognition motif 1 (RRM1) found in (U)-binding-splicing factor PUF60 and similar proteins; This subfamily corresponds to the RRM1 of PUF60, also termed FUSE-binding protein-interacting repressor (FBP-interacting repressor or FIR), or Ro-binding protein 1 (RoBP1), or Siah-binding protein 1 (Siah-BP1). PUF60 is an essential splicing factor that functions as a poly-U RNA-binding protein required to reconstitute splicing in depleted nuclear extracts. Its function is enhanced through interaction with U2 auxiliary factor U2AF65. PUF60 also controls human c-myc gene expression by binding and inhibiting the transcription factor far upstream sequence element (FUSE)-binding-protein (FBP), an activator of c-myc promoters. PUF60 contains two central RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a C-terminal U2AF (U2 auxiliary factor) homology motifs (UHM) that harbors another RRM and binds to tryptophan-containing linear peptide motifs (UHM ligand motifs, ULMs) in several nuclear proteins. Research indicates that PUF60 binds FUSE as a dimer, and only the first two RRM domains participate in the single-stranded DNA recognition.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIK-------PGgiqvrNNKQQGYCfgFVEF-------LSLNSMNSAIqaspvpIGG 370
Cdd:cd12370    3 VYVGSIYFELGEDTIRQAFAPFGPIKsidmswdPV-----TMKHKGFA--FVEYevpeaaqLALEQMNGVM------LGG 69

                 .
gi 955337014 371 R 371
Cdd:cd12370   70 R 70

RNA recognition motif 1 (RRM1) found in chloroplastic plastid-specific 30S ribosomal protein 2 (PSRP-2) and similar proteins; PSRP-2, also called chloroplastic 30S ribosomal protein 2, or chloroplastic small ribosomal subunit protein cS22, is a component of the chloroplast ribosome (chloro-ribosome), a dedicated translation machinery responsible for the synthesis of chloroplast genome-encoded proteins, including proteins of the transcription and translation machinery and components of the photosynthetic apparatus. It binds single strand DNA (ssDNA) and RNA in vitro. It exhibits RNA chaperone activity and regulates negatively resistance responses to abiotic stresses during seed germination (e.g. salt, dehydration, and low temperature) and seedling growth (e.g. salt). The family also includes Nicotiana sylvestris chloroplastic 33 kDa ribonucleoprotein (NsCP33) and Arabidopsis thaliana chloroplastic 31 kDa ribonucleoprotein (AtCP31A). NsCP33 may be involved in splicing and/or processing of chloroplast RNA's. AtCP31A, also called RNA-binding protein 1/2/3 (AtRBP33), or RNA-binding protein CP31A, or RNA-binding protein RNP-T, or RNA-binding protein cp31, is required for specific RNA editing events in chloroplasts and stabilizes specific chloroplast mRNAs, as well as for normal chloroplast development under cold stress conditions by stabilizing transcripts of numerous mRNAs under these conditions. CP31A may modulate telomere replication through RNA binding domains. Members in this family contain two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). The model corresponds to the first RRM motif.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIKpgGIQVRNNKQQGYC--FGFVEFLSLNSMNSAIQA-SPVPIGGRQAVVEI 377
Cdd:cd21609    2 LYVGNIPRNVTSEELAKIFEEAGTVE--IAEVMYDRYTGRSrgFGFVTMGSVEDAKAAIEKlNGTEVGGREIKVNI 75

RNA recognition motif (RRM) found in ras GTPase-activating protein-binding protein G3BP1, G3BP2 and similar proteins; This subfamily corresponds to the RRM domain in the G3BP family of RNA-binding and SH3 domain-binding proteins. G3BP acts at the level of RNA metabolism in response to cell signaling, possibly as RNA transcript stabilizing factors or an RNase. Members include G3BP1, G3BP2 and similar proteins. These proteins associate directly with the SH3 domain of GTPase-activating protein (GAP), which functions as an inhibitor of Ras. They all contain an N-terminal nuclear transfer factor 2 (NTF2)-like domain, an acidic domain, a domain containing PXXP motif(s), an RNA recognition motif (RRM), and an Arg-Gly-rich region (RGG-rich region, or arginine methylation motif).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 955337014 303 HSIYIRNLPLNVTVAQLELEFKKFGPIKPGGIQVRNNKQQGYCFGFVEFLSLNSMNSAIQASPVPIGGRQAV-VEIKR 379
Cdd:cd12229    4 HQLFVGNLPHDITEDELKEFFSRFGNVLELRINSKGGGGRLPNFGFVVFDDPEAVQKILANKPIMFRGEHRLnVEEKK 81

RNA recognition motif 2 (RRM2) found in squamous cell carcinoma antigen recognized by T-cells 3 (SART3) and similar proteins; This subfamily corresponds to the RRM2 of SART3, also termed Tat-interacting protein of 110 kDa (Tip110), is an RNA-binding protein expressed in the nucleus of the majority of proliferating cells, including normal cells and malignant cells, but not in normal tissues except for the testes and fetal liver. It is involved in the regulation of mRNA splicing probably via its complex formation with RNA-binding protein with a serine-rich domain (RNPS1), a pre-mRNA-splicing factor. SART3 has also been identified as a nuclear Tat-interacting protein that regulates Tat transactivation activity through direct interaction and functions as an important cellular factor for HIV-1 gene expression and viral replication. In addition, SART3 is required for U6 snRNP targeting to Cajal bodies. It binds specifically and directly to the U6 snRNA, interacts transiently with the U6 and U4/U6 snRNPs, and promotes the reassembly of U4/U6 snRNPs after splicing in vitro. SART3 contains an N-terminal half-a-tetratricopeptide repeat (HAT)-rich domain, a nuclearlocalization signal (NLS) domain, and two C-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....
gi 955337014 301 EGHSIYIRNLPLNVTVAQLELEFKKFGPIKpgGIQV---RNNKQQGycFGFVEF 351
Cdd:cd12392    1 EKNKLFVKGLPFSCTKEELEELFKQHGTVK--DVRLvtyRNGKPKG--LAYVEY 50

RNA recognition motif 4 (RRM4) found in type I polyadenylate-binding proteins; This subfamily corresponds to the RRM4 of type I poly(A)-binding proteins (PABPs), highly conserved proteins that bind to the poly(A) tail present at the 3' ends of most eukaryotic mRNAs. They have been implicated in theThe CD corresponds to the RRM. regulation of poly(A) tail length during the polyadenylation reaction, translation initiation, mRNA stabilization by influencing the rate of deadenylation and inhibition of mRNA decapping. The family represents type I polyadenylate-binding proteins (PABPs), including polyadenylate-binding protein 1 (PABP-1 or PABPC1), polyadenylate-binding protein 3 (PABP-3 or PABPC3), polyadenylate-binding protein 4 (PABP-4 or APP-1 or iPABP), polyadenylate-binding protein 5 (PABP-5 or PABPC5), polyadenylate-binding protein 1-like (PABP-1-like or PABPC1L), polyadenylate-binding protein 1-like 2 (PABPC1L2 or RBM32), polyadenylate-binding protein 4-like (PABP-4-like or PABPC4L), yeast polyadenylate-binding protein, cytoplasmic and nuclear (PABP or ACBP-67), and similar proteins. PABP-1 is an ubiquitously expressed multifunctional protein that may play a role in 3' end formation of mRNA, translation initiation, mRNA stabilization, protection of poly(A) from nuclease activity, mRNA deadenylation, inhibition of mRNA decapping, and mRNP maturation. Although PABP-1 is thought to be a cytoplasmic protein, it is also found in the nucleus. PABP-1 may be involved in nucleocytoplasmic trafficking and utilization of mRNP particles. PABP-1 contains four copies of RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), a less well conserved linker region, and a proline-rich C-terminal conserved domain (CTD). PABP-3 is a testis-specific poly(A)-binding protein specifically expressed in round spermatids. It is mainly found in mammalian and may play an important role in the testis-specific regulation of mRNA homeostasis. PABP-3 shows significant sequence similarity to PABP-1. However, it binds to poly(A) with a lower affinity than PABP-1. Moreover, PABP-1 possesses an A-rich sequence in its 5'-UTR and allows binding of PABP and blockage of translation of its own mRNA. In contrast, PABP-3 lacks the A-rich sequence in its 5'-UTR. PABP-4 is an inducible poly(A)-binding protein (iPABP) that is primarily localized to the cytoplasm. It shows significant sequence similarity to PABP-1 as well. The RNA binding properties of PABP-1 and PABP-4 appear to be identical. PABP-5 is encoded by PABPC5 gene within the X-specific subinterval, and expressed in fetal brain and in a range of adult tissues in mammalian, such as ovary and testis. It may play an important role in germ cell development. Moreover, unlike other PABPs, PABP-5 contains only four RRMs, but lacks both the linker region and the CTD. PABP-1-like and PABP-1-like 2 are the orthologs of PABP-1. PABP-4-like is the ortholog of PABP-5. Their cellular functions remain unclear. The family also includes the yeast PABP, a conserved poly(A) binding protein containing poly(A) tails that can be attached to the 3'-ends of mRNAs. The yeast PABP and its homologs may play important roles in the initiation of translation and in mRNA decay. Like vertebrate PABP-1, the yeast PABP contains four RRMs, a linker region, and a proline-rich CTD as well. The first two RRMs are mainly responsible for specific binding to poly(A). The proline-rich region may be involved in protein-protein interactions.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 955337014 302 GHSIYIRNLPLNVTVAQLELEFKKFGPIKPGGIqVRNNKQQGYCFGFVEFLS-------LNSMNSAI 361
Cdd:cd12381    1 GVNLYVKNLDDTIDDEKLREEFSPFGTITSAKV-MTDEGGRSKGFGFVCFSSpeeatkaVTEMNGRI 66

RNA recognition motif 3 (RRM3) found in vertebrate heterogeneous nuclear ribonucleoprotein M (hnRNP M); This subgroup corresponds to the RRM3 of hnRNP M, a pre-mRNA binding protein that may play an important role in the pre-mRNA processing. It also preferentially binds to poly(G) and poly(U) RNA homopolymers. Moreover, hnRNP M is able to interact with early spliceosomes, further influencing splicing patterns of specific pre-mRNAs. hnRNP M functions as the receptor of carcinoembryonic antigen (CEA) that contains the penta-peptide sequence PELPK signaling motif. In addition, hnRNP M and another splicing factor Nova-1 work together as dopamine D2 receptor (D2R) pre-mRNA-binding proteins. They regulate alternative splicing of D2R pre-mRNA in an antagonistic manner. hnRNP M contains three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and an unusual hexapeptide-repeat region rich in methionine and arginine residues (MR repeat motif).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 955337014 305 IYIRNLPLNVTVAQLELEFKKFGPIKPGGIQVRNNKQQGyCfGFVEFLSLNSMNSAIQA-SPVPIGGRQAVVEIKR 379
Cdd:cd12661    2 IFVRNLPFDFTWKMLKDKFNECGHVLYADIKMENGKSKG-C-GVVRFESPEVAERACRMmNGIKLNGREIDVRIDR 75