The amino-terminal domain of the Golgi protein Giantin interacts directly with the vesicle-tethering protein p115

Giantin is thought to form a complex with p115 and Golgi matrix protein 130 , which is involved in the reassembly of Golgi cisternae and stacks at the end of mitosis. The complex is involved in the tethering of coat protomer I vesicles to Golgi membranes and the initial stacking of reforming cisterna e, Here we show that the NH2-terminal 15% of Giantin suffices to bind p115 in vitro and in vivo and to block cell-free Golgi reassembly. Because Giant in is a long, rod-like protein anchored to the membrane by its extreme COOH terminus, these results support the idea of a long, flexible tether linkin g vesicles and cisternae.