Biology:PTBP1

Short description: Protein-coding gene in the species Homo sapiens

Generic protein structure example

Polypyrimidine tract-binding protein 1 is a protein that in humans is encoded by the PTBP1 gene.

This gene belongs to the subfamily of ubiquitously expressed heterogeneous nuclear ribonucleoproteins (hnRNPs). The hnRNPs are RNA-binding proteins and they complex with heterogeneous nuclear RNA (hnRNA). These proteins are associated with pre-mRNAs in the nucleus and appear to influence pre-mRNA processing and other aspects of mRNA metabolism and transport. While all of the hnRNPs are present in the nucleus, some seem to shuttle between the nucleus and the cytoplasm. The hnRNP proteins have distinct nucleic acid binding properties. The protein encoded by this gene has four repeats of quasi-RNA recognition motif (RRM) domains that bind RNAs. This protein binds to the intronic polypyrimidine tracts that requires pre-mRNA splicing and acts via the protein degradation ubiquitin-proteasome pathway. It may also promote the binding of U2 snRNP to pre-mRNAs. This protein is localized in the nucleoplasm and it is also detected in the perinucleolar structure. Alternatively spliced transcript variants encoding different isoforms have been described.

Evolution

In brains of mammals, transcripts from the PTBP1 gene are missing one exon (exon 9) that is included in the brains of other vertebrates, as a result of alternative splicing. This contributes to the evolutionary difference between the nervous system of mammals and other vertebrates.

Interactions

PTBP1 has been shown to interact with HNRPK, PCBP2, SFPQ and HNRNPL.

This gene is targeted by the microRNA miR-124. During neuronal differentiation, miR-124 reduces PTBP1 levels, leading to the accumulation of correctly spliced PTBP2 mRNA and a dramatic increase in PTBP2 protein.

Further reading

• "Microsequences of 145 proteins recorded in the two-dimensional gel protein database of normal human epidermal keratinocytes". Electrophoresis 13 (12): 960–969. December 1992. doi:10.1002/elps.11501301199. PMID 1286667. 
• "hnRNP I, the polypyrimidine tract-binding protein: distinct nuclear localization and association with hnRNAs". Nucleic Acids Research 20 (14): 3671–3678. July 1992. doi:10.1093/nar/20.14.3671. PMID 1641332. 
• "Characterization of cDNAs encoding the polypyrimidine tract-binding protein". Genes & Development 5 (7): 1224–1236. July 1991. doi:10.1101/gad.5.7.1224. PMID 1906035. 
• "Assignment of the human gene encoding heterogeneous nuclear RNA ribonucleoprotein I (PTB) to chromosome 14q23-q24.1". Genomics 27 (3): 553–555. June 1995. doi:10.1006/geno.1995.1093. PMID 7558043. 
• "Cloning and characterization of PSF, a novel pre-mRNA splicing factor". Genes & Development 7 (3): 393–406. March 1993. doi:10.1101/gad.7.3.393. PMID 8449401. 
• "Identification of a group of cellular cofactors that stimulate the binding of RNA polymerase II and TRP-185 to human immunodeficiency virus 1 TAR RNA". The Journal of Biological Chemistry 271 (8): 4201–4208. February 1996. doi:10.1074/jbc.271.8.4201. PMID 8626763. 
• "Specific binding of polypyrimidine tract binding protein and hnRNP A1 to HIV-1 CRS elements". Virus Genes 12 (3): 275–285. 1997. doi:10.1007/bf00284648. PMID 8883365. 
• "The dynamic organization of the perinucleolar compartment in the cell nucleus". The Journal of Cell Biology 137 (5): 965–974. June 1997. doi:10.1083/jcb.137.5.965. PMID 9166399. 
• "Determination of functional domains in polypyrimidine-tract-binding protein". The Biochemical Journal 331 (Pt 1): 169–175. April 1998. doi:10.1042/bj3310169. PMID 9512476. 
• "Polypyrimidine tract-binding protein interacts with HnRNP L". FEBS Letters 425 (3): 401–406. April 1998. doi:10.1016/S0014-5793(98)00269-5. PMID 9563502. 
• "Differential nuclear localization and nuclear matrix association of the splicing factors PSF and PTB". Journal of Cellular Biochemistry 76 (4): 559–566. January 2000. doi:10.1002/(SICI)1097-4644(20000315)76:4<559::AID-JCB4>3.0.CO;2-U. PMID 10653975. 
• "Protein-protein interaction among hnRNPs shuttling between nucleus and cytoplasm". Journal of Molecular Biology 298 (3): 395–405. May 2000. doi:10.1006/jmbi.2000.3687. PMID 10772858. 
• "Structure of tandem RNA recognition motifs from polypyrimidine tract binding protein reveals novel features of the RRM fold". The EMBO Journal 19 (12): 3132–3141. June 2000. doi:10.1093/emboj/19.12.3132. PMID 10856256. 
• "Cooperative assembly of an hnRNP complex induced by a tissue-specific homolog of polypyrimidine tract binding protein". Molecular and Cellular Biology 20 (20): 7463–7479. October 2000. doi:10.1128/MCB.20.20.7463-7479.2000. PMID 11003644. 
• "Human pre-mRNA cleavage factor II(m) contains homologs of yeast proteins and bridges two other cleavage factors". The EMBO Journal 19 (21): 5895–5904. November 2000. doi:10.1093/emboj/19.21.5895. PMID 11060040. 
• "Role of polypyrimidine tract binding protein in the function of the hepatitis B virus posttranscriptional regulatory element". Journal of Virology 75 (22): 10779–10786. November 2001. doi:10.1128/JVI.75.22.10779-10786.2001. PMID 11602719. 
• "Raver1, a dual compartment protein, is a ligand for PTB/hnRNPI and microfilament attachment proteins". The Journal of Cell Biology 155 (5): 775–786. November 2001. doi:10.1083/jcb.200105044. PMID 11724819. 
• "Nucleocytoplasmic shuttling of polypyrimidine tract-binding protein is uncoupled from RNA export". Molecular Biology of the Cell 12 (12): 3808–3820. December 2001. doi:10.1091/mbc.12.12.3808. PMID 11739782.