Multipronged interaction of the COG complex with intracellular membranes.

The conserved oligomeric Golgi complex is a peripheral membrane protein complex that orchestrates the tethering and fusion of intra-Golgi transport carriers with Golgi membranes. In this study we have investigated the membrane attachment of the COG complex and it's on/off dynamic on Golgi membranes. Several complimentary approaches including knock-sideways depletion, FRAP, and FLIP revealed that assembled COG complex is not diffusing from Golgi periphery in live HeLa cells. Moreover, COG subunits remained membrane-associated even in COG4 and COG7 depleted cells when Golgi architecture was severely affected. Overexpression of myc-tagged COG sub-complexes revealed that different membrane-associated COG partners including β-COP, p115 and SNARE STX5 preferentially bind to different COG assemblies, indicating that COG subunits interact with Golgi membranes in a multipronged fashion.