RNA binding protein that binds to the poly-A tract of mRNA molecules. Associates with the 40S ribosomal subunit and with polysomes. Plays a role in the regulation of mRNA translation. Plays a role in the regulation of cell morphology and cytoskeletal organization. Interacts (via N-terminal region) with PABPC1. Interacts with RACK1. Localized throughout the cytosol. Partially localized in stress granules in response to arsenite treatment.