BIOL 230W Lecture Notes - Lecture 36: Lipid Bilayer Fusion, Snap25, Hydrolysis
Document Summary
Two families: vsnares (vesicle, make up snare complex together tsnares (target) Helps mediate membrane fusion between specific compartments. Docking: vsnares bind to tsnares, snap25 is a specialized tsnare. Helps form tight complex between snare proteins. Final snare complex formation (and fusion) requires gtp hydrolysis. Small g-proteins do not release gtp after hydrolysis of gdp. Requires gef to facilitate gdp gtp exchange. Gefs play a pivotal role in regulating g-proteins: activity of gef rises g-protein more active. Rab is active during non-vesicular membrane exchange. Gdi: gdp dissociation inhibitor: keeps g-protein inactive, masks lipids, non-functional gdi would prevent rab from associating with donor membrane. Eventually will slow down endocytosis because there will be no rab in plasma membrane. Gap: gtpase activating proteins: gaps bind to g-protein/gtp to change g-protein in shape, facilitating g-protein hydrolysis, overactive gap would accelerate gtp hydrolysis. More likely to find g-protein in off state. Gef: guanine nucleotide exchange factors: an underactive gdf causes a less active g-protein.
