Interaction of synaptophysin with the AP-1 adaptor protein gamma-adaptin.

Synaptophysin is one of the most abundant proteins of the synaptic vesicle membrane. Here, we selected the cytoplasmic carboxyterminal region of synaptophysin to search for interacting proteins by using the yeast two-hybrid system. This identified gamma-adaptin, a component of the AP-1 adaptor complex, as a synaptophysin binding protein. An anti-synaptophysin antibody coimmunoprecipitated gamma-adaptin from brain extracts, and immunocytochemistry disclosed a partial colocalization of synaptophysin and gamma-adaptin in the perinuclear region of cultured hippocampal neurons. Our results are consistent with synaptophysin serving as a docking site for AP-1 during clathrin-dependent vesicle budding and/or kinesin-based transport reactions.