Binds the poly(A) tail of mRNA. May be involved in cytoplasmic regulatory processes of mRNA metabolism. Can probably bind to cytoplasmic RNA sequences other than poly(A) in vivo (By similarity). Identified in a IGF2BP1-dependent mRNP granule complex containing untranslated mRNAs. Interacts with NFX1. Interacts with ZFC3H1 in a RNase-sensitive manner (PubMed:27871484). Localized in cytoplasmic mRNP granules containing untranslated mRNAs. Expressed at low levels in resting normal T cells; following T-cell activation, however, mRNA levels are rapidly up-regulated. Arg-518 is dimethylated, probably to asymmetric dimethylarginine. Belongs to the polyadenylate-binding protein type-1 family.