UNASSIGNED: In eukaryotic cells, membrane-bound vesicles carry cargo between intracellular compartments, to and from the cell surface, and into the extracellular environment. Many conserved families of proteins are required for properly localized vesicle fusion, including the multisubunit tethering complexes (MTCs) and the SNARE complexes. These protein complexes work together to promote proper vesicle fusion in intracellular trafficking pathways. However, the mechanism by which the exocyst, the exocytosis-specific MTC, interacts with the exocytic SNAREs to mediate vesicle targeting and fusion is currently unknown. We previously demonstrated that the @entity375 exocyst subunit @entity18739 directly bound the plasma membrane SNARE protein @entity68832 in vitro and that @entity18739 inhibited the assembly of the binary @entity52111 : @entity68832 SNARE complex. Therefore, we hypothesized that the interaction between @entity18739 and @entity68832 prevented the assembly of premature SNARE complexes at sites of exocytosis. In order to map the determinants of this interaction, we used cross-linking and mass spectrometry analyses to identify residues required for binding. Mutation of residues identified by this approach resulted in a growth defect when introduced into @entity375 . Contrary to our previous hypothesis, we discovered that @entity18739 does not change the rate of SNARE assembly, but rather binds both the binary @entity68832 : @entity52111 and ternary @entity68832 : @entity52111 : @entity68833 SNARE complex. Together, these results suggest a new model wherein @entity18739 promotes SNARE complex assembly, similar to the role proposed for other tether subunit-SNARE interactions.

The Exocyst Subunit XXXX Interacts with Assembled Exocytic SNARE Complexes.

@entity52111 :: ('855844(Tax:4932)', 'Gene') :: ['Sso1'] @entity68833 :: ('854505(Tax:4932)', 'Gene') :: ['Snc2'] @entity18739 :: ('854742(Tax:4932)', 'Gene') :: ['Sec6'] @entity375 :: ('4932', 'Species') :: ['yeast', 'Saccharomyces cerevisiae'] @entity68832 :: ('852892(Tax:4932)', 'Gene') :: ['Sec9']
@entity18739 :: (854742(Tax:4932),Gene) :: ['Sec6']
