Interaction of BIG2, a brefeldin A-inhibited guanine nucleotide-exchange protein, with exocyst protein Exo70.

ABSTRACT: Guanine nucleotide-exchange proteins activate ADP-ribosylation factors by accelerating the replacement of bound GDP with GTP. Mammalian brefeldin A-inhibited guanine nucleotide-exchange proteins, BIG1 and BIG2, are important activators of ADP-ribosylation factors for vesicular trafficking. To identify proteins that interact with BIG2, we used cDNA constructs encoding BIG2 sequences in a yeast two-hybrid screen of a human heart library. Clone p2-5-3, encoding a form of human exocyst protein Exo70, interacted with BIG2 amino acids 1-643 and 1-832, but not 644-832, which was confirmed by coimmunoprecipitation of in vitro-translated BIG2 N-terminal segments and 2-5-3. By immunofluorescence microscopy, endogenous BIG2 and Exo70 in HepG2 cells were visualized at Golgi membranes and apparently at

SUBMITTER: Xu KF 

PROVIDER: S-EPMC549493 | biostudies-literature | 2005 Feb

REPOSITORIES: biostudies-literature