Immunocytochemical characterization of clathrin-associated proteins (CAPs). I. Neuronal distribution of CAPs, a component of clathrin-coated vesicles.

: Clathrin-associated proteins (CAPs) elicited antibodies in rabbits that were affinity-purified using CAPs-conjugated CNBr-Sepharose 4B. Anti-CAPs IgG formed immunoprecipitates with CAPs and with the clathrin-CAPs complex. Indirect immunoperoxidase-labeling in sections of rat brain cortex using anti-CAPs and anti-clathrin IgG yielded similar staining patterns. Coated perinuclear cisternae and coated vesicles became stained and easily distinguished. Intense staining also was found in synaptic boutons with label between most synaptic vesicles and as a thick crust surrounding coated vesicles. The data demonstrate that clathrin and CAPs polypeptides are in identical subcellular locations.