PROTEIN-PROTEIN INTERACTIONS OF THE YEAST GOLGI T-SNARE SED5 PROTEIN DISTINCT FROM ITS NEURAL PLASMA-MEMBRANE COGNATE SYNTAXIN-1

Targeting of vesicles to the acceptor membrane in protein transport de pends on membrane proteins called SNAREs. Saccharomyces cerevisiae Gol gi t-SNARE Sed5 protein and its neural cognate syntaxin 1 have similar three cy-helices which are predicted to form coiled coils. me dissect ed the helices of Sed5 and found several characteristics unexpectedly distinct from those of syntaxin 1. Most importantly, only the N-termin al helix is responsible for the binding of Sly1 protein while almost t he entire molecule of syntaxin is necessary for the binding of the cog nate, Munc-18. The N-terminal region of Sed5 protein also binds to the C-terminal helix and Sly1 protein interfered this binding. (C) 1998 A cademic Press.