Team Effort by TRAPP Forces a Nucleotide Fumble

TRAPPI is a multisubunit protein complex on the Golgi that activates the small GTPase Ypt1p to facilitate the receipt of transport vesicles inbound from the endoplasmic reticulum. now present structural and biochemical analyses of yeast TRAPPI in a complex with Ypt1p revealing a unique mechanism by which TRAPPI catalyzes guanine nucleotide exchange.