RAB GTPASES - MASTER REGULATORS OF MEMBRANE TRAFFICKING

Rab GTPases are thought to be likely to catalyze the accurate associat ion of pairs of targeting molecules located on the surfaces of transpo rt vesicles with their corresponding membrane accepters. Advances duri ng the past year have solidified our understanding of the mechanisms b y which Rab proteins are recruited onto nascent transport vesicles and retrieved from their fusion targets. Functional analyses of Rab prote ins in living cells have led to the surprising observation that vesicl es do not seem to form if the appropriate Rab protein, in its GTP-boun d conformation, is not present.