Polypyrimidine tract-binding protein 1 is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
that in humans is encoded by the ''PTBP1''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
.
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
Alternative splicing, or alternative RNA splicing, or differential splicing, is an alternative splicing process during gene expression that allows a single gene to code for multiple proteins. In this process, particular exons of a gene may be ...
. This contributes to the evolutionary difference between the nervous system of mammals and other vertebrates.
Interactions
PTBP1 has been shown to
interact
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with
HNRPK
Heterogeneous nuclear ribonucleoprotein K (also protein K) is a protein that in humans is encoded by the ''HNRNPK'' gene. It is found in the cell nucleus that binds to pre-messenger RNA (mRNA) as a component of heterogeneous ribonucleoprotein par ...
,
PCBP2
Poly(rC)-binding protein 2 is a protein that in humans is encoded by the ''PCBP2'' gene.
Function
The protein encoded by this gene appears to be multifunctional. It along with PCBP-1 and hnRNPK corresponds to the major cellular poly(rC)-binding ...
,
[ ]SFPQ
Splicing factor, proline- and glutamine-rich is a protein that in humans is encoded by the ''SFPQ'' gene.
Interactions
SFPQ has been shown to interact with PTBP1, NONO, CDC5L and Ubiquitin C
Polyubiquitin-C is a protein encoded by the ''UBC' ...
HNRNPL
Heterogeneous nuclear ribonucleoprotein L is a protein that in humans is encoded by the ''HNRNPL'' gene.
Function
Heterogeneous nuclear RNAs (hnRNAs) which include mRNA precursors and mature mRNAs are associated with specific proteins to form ...
.PTBP2
Polypyrimidine tract binding protein 2, also known as PTBP2, is a protein which in humans is encoded by the ''PTBP2'' gene.
Function
The protein encoded by this gene binds to the intronic cluster of cis-regulatory element, RNA regulatory elemen ...
mRNA and a dramatic increase in PTBP2 protein.
References
Further reading
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{{Nucleus