Figure 8.

A model for AP-1/clathrin coat recruitment and the role of GTP hydrolysis. Gray arrows indicate recruitment of AP-1 to the membrane via Arf1·GTP and either a cytosolic factor (CF) or directly to cargo proteins with tyrosine motifs (Y). On interaction with cargo, AP-1 oligomerizes. GTP hydrolysis induced by ArfGAP1 (not drawn for simplicity) causes AP-1 dissociation unless the clathrin layer has been assembled. Arf1·GTP hydrolysis by ArfGAP1 is differentially stimulated by the AP-1/CF complex, the AP-1/cargo oligomers, and by membrane curvature limiting the time available for the next step in productive coat formation and preparing the adaptor layer for subsequent disassembly, respectively. See also Discussion.