Figure 1.

Hypothetical model for the role of different clathrin/AP complexes in SV recycling. (A) SVs are clustered near the active zone (AZ). (B) In wild type SVs are recycled mainly by CME. Sustained high-level activity induces BE involving formation of vacuoles. Fission likely involves dynamin (red circles). SV reformation from vacuoles occurs, at least in part, by clathrin-dependent budding. (C) Nerve terminals of AP-1/σ1B-KO mice display reduced numbers of SVs. Clathrin-coated buds accumulate on vacuoles that might have originated from BE. Buds may contain AP-1/σ1A, AP-2, or AP-3.