N-ETHYLMALEIMIDE-SENSITIVE FACTOR (NSF) AND ALPHA-SOLUBLE NSF ATTACHMENT PROTEINS (SNAP) MEDIATE DISSOCIATION OF GS28-SYNTAXIN-5 GOLGI SNAPRECEPTORS (SNARE) COMPLEX

Golgi soluble N-ethylmaleimide-sensitive factor attachment protein rec eptors (SNAREs) GS28 and syntaxin 5 can be reciprocally coimmunoprecip itated from Golgi extracts, suggesting that they exist in a protein co mplex. When Golgi extract is preincubated with soluble NSF attachment proteins (alpha-SNAP) and N-ethylmaleimide-sensitive factor (NSF) unde r conditions that allow ATP hydrolysis by NSF, GS28 and syntaxin 5 bec ome dissociated, GS28 and syntaxin 5 remain in a protein complex when Golgi extract is preincubated with similar amounts of alpha-SNAP and N SF under conditions that prevent ATP hydrolysis by NSF, suggesting tha t ATP hydrolysis by NSF is necessary for dissociating the GS28-syntaxi n 5 complex. Since preincubation of Gels extract with either alpha-SNA P or NSF alone has no effect on the GS28-syntaxin 5 complex, a concert ed action of alpha-SNAP and NSF therefore mediates the dissociation of the GS28-syntaxin 5 complex, Furthermore, GS28 but not syntaxin 5 is capable of binding to immobilized alpha-SNAP when the GS28-syntaxin 5 complex is dissociated.