PTBP3

PTBP3, or polypyrimidine tract-binding protein 3, is an RNA-binding protein that belongs to the polypyrimidine tract-binding protein (PTB) family. It is a paralog of PTBP1 and PTBP2 and shares the characteristic domain architecture of this family, typically including four RNA recognition motif (RRM) domains. PTBP3 binds to polypyrimidine-rich sequences in pre-mRNA and participates in post-transcriptional regulation.

In terms of function, PTBP3 binds CU-rich regions within transcripts and influences splicing outcomes. Through interactions with intronic or exonic polypyrimidine tracts, it can modulate exon inclusion or skipping, often acting as a splicing regulator in a context-dependent manner. Beyond splicing, PTBP3 may also impact mRNA stability and translation in certain targets, contributing to the broader regulation of gene expression at the post-transcriptional level. Its activity is coordinated with other splicing factors to shape transcriptomes during development and differentiation.

Expression studies indicate that PTBP3 has a distinct tissue distribution compared with its paralogs PTBP1 and PTBP2, with detection in several tissues including hematopoietic cells and placenta, though expression levels can vary by tissue, developmental stage, and species. The precise physiological roles of PTBP3 are still being investigated, and its regulatory networks are being defined in relation to other RNA-binding proteins.

In research contexts, altered PTBP3 expression or function has been observed in some cancers and developmental models, suggesting potential involvement in disease-related splicing programs. Current work continues to clarify its contributions to normal biology and pathological states.

See also: polypyrimidine tract-binding protein family; RNA-binding proteins; alternative splicing.