Rab27 Effector Granuphilin Promotes the Plasma Membrane Targeting of Insulin Granules via Interaction with Syntaxin 1a

摘要: Secretory vesicle exocytosis is a highly regulated process involving targeting, priming, and membrane fusion. Rabs SNAREs play central role in executing these processes. We have shown recently that Rab27a its effector, granuphilin, are involved the of insulin-containing secretory granules through direct interaction with plasma syntaxin 1a pancreatic beta cells. Here, we demonstrate fluorescence-labeled insulin peripherally accumulated cells overexpressing granuphilin. The peripheral location well overlapped both localizations granuphilin 1a. targeting promoted by wild-type but not mutants defective binding to either or Granuphilin directly binds H3 domain containing SNARE motif. Moreover, introduction into induces dissociation native granuphilin-syntaxin complex marked reduction newly docked granules. These results indicate plays tethering an formation three proteins may contribute specificity during