100-kDa polypeptides in peripheral clathrin-coated vesicles are required for receptor-mediated endocytosis

The role of the 100-kDa polypeptide components of clathrin-coated vesicles in endocytosis was investigated by microinjection of specific monoclonal antibodies. Receptor-mediated uptake of transferrin and liposomes was quantitatively inhibited. These results show that the 100-kDa polypeptides are directly involved in localized clathrin assembly at the cell periphery and are markers for the endocytic pathway. This demonstrates an in situ function of these polypeptides and the protein complexes in which they are found.