CLATHRIN-COATED VESICLES FROM HUMAN PLACENTA CONTAIN GTP-BINDING PROTEINS

Biochemical and morphological techniques were used to investigate the GTP-binding proteins of clathrin-coated vesicles. Binding of [3H]GTP to clathrin coats was demonstrated by electron microscopic autoradiography. Purified coated vesicles bound 5.2 pmol [35S]GTPγS/mg protein. Addition of GTP or GTPγS, but not ATP nor GMP, inhibited binding of [35S]GTPγS to intact coated vesicles and Triton X-100-extracted coats. A series of 23-24 kDa GTP-binding proteins with isoelectric points between pH 5-8 were detected in coated vesicles. We suggest that the low molecular weight ras-like GTP-binding protein(s) play a role in regulating vesicle-mediated protein transport or signal transduction within intracellular organelles. © 1991.