PABPC1

PABPC1 stands for poly(A) binding protein cytoplasmic 1, an evolutionarily conserved RNA-binding protein found in eukaryotes. It binds to the poly(A) tails of most polyadenylated mRNAs in the cytoplasm, playing a central role in regulating mRNA stability and translation.

The protein contains four RNA recognition motifs (RRM1–RRM4) that mediate binding to the poly(A) tail, and a C-terminal MLLE (PABC) domain that mediates interactions with other proteins. This modular architecture enables PABPC1 to coordinate mRNA metabolism through multiple protein–protein and protein–RNA interactions.

Functionally, PABPC1 stabilizes transcripts by protecting the poly(A) tail from rapid deadenylation and promotes translation initiation by facilitating the formation of a closed-loop mRNA structure. This loop is achieved in part by bridging the poly(A) tail to the 5' cap via interactions with translation factors such as eIF4G and eIF4A. PABPC1 also participates in mRNA decay pathways and can influence mRNA localization and turnover in the cytoplasm.

PABPC1 engages with a range of partners, including PAIP1 and PAIP2, as well as components of the deadenylation machinery. It localizes primarily to the cytoplasm and is found in processing bodies and stress granules under certain cellular conditions, reflecting its involvement in dynamic mRNA regulation. The protein is broadly expressed across human tissues and is a key member of the cytoplasmic poly(A) binding protein family.

In humans, the PABPC1 gene encodes this protein, which serves as a representative and well-studied member of the PABP family involved in post-transcriptional control of gene expression through poly(A) binding.