[5][6] Poly(A)-binding proteins (PABPs) bind to the poly(A) tail present at the 3-prime ends of most eukaryotic mRNAs.

PABPC4 or IPABP (inducible PABP) was isolated as an activation-induced T-cell mRNA encoding a protein.

It is suggested that PABPC4 might be necessary for regulation of stability of labile mRNA species in activated T cells.

PABPC4 was also identified as an antigen, APP1 (activated-platelet protein-1), expressed on thrombin-activated rabbit platelets.

PABPC4 may also be involved in the regulation of protein translation in platelets and megakaryocytes or may participate in the binding or stabilization of polyadenylates in platelet dense granules.