Structure-function study of the N-terminal domain of exocyst subunit Sec3.
The exocyst is an evolutionarily conserved octameric complex involved in polarized exocytosis from yeast to humans. The Sec3 subunit of the exocyst acts as a spatial landmark for exocytosis through its ability to bind phospholipids and small GTPases. The structure of the N-terminal domain of Sec3 (Sec3N) was determined ab initio and defines a new subclass of pleckstrin homology (PH) domains along with a new family of proteins carrying this domain. Respectively, N- and C-terminal to the PH domain Sec3N presents an additional alpha-helix and two beta-strands that mediate dimerization through domain swapping. The structure identifies residues responsible for phospholipid binding, which when mutated in cells impair the localization of exocyst components at the plasma membrane and lead to defects in exocytosis. Through its ability to bind the small GTPase Cdc42 and phospholipids, the PH domain of Sec3 functions as a coincidence detector at the plasma membrane.
SciCrunch is a data sharing and display platform. Anyone can create a custom portal where they can select searchable subsets of hundreds of data sources, brand their web pages and create their community. SciCrunch will push data updates automatically to all portals on a weekly basis. User communities can also add their own data to scicrunch, however this is not currently a free service.