CHARACTERIZATION OF A NOVEL PLATELET-DERIVED GROWTH FACTOR-ASSOCIATEDPROTEIN

A novel mitogen-associated protein was isolated from a rat neural reti na cell line. The protein copurified with platelet-derived growth fact or (PDGF)-A and was therefore termed PDGF-associated protein (PAP). cD NAs corresponding to the protein were characterized from both rat and human cDNA libraries. PAP binds to PDGF with low affinity and enhances the mitogenic effect of PDGF-A but lowers the mitogenic activity of P DGF-B. PAP mRNA is abundant in the brain of newborn rats and is found in several other tissues.