This family consists of several Rab5-interacting protein (RIP5or Rab5ip ) sequences. The ras-related GTPase rab5 israte-limiting for homotypic early endosome fusion. Rab5iprepresents a novel rab5 interacting protein that may function onendocytic vesicles as a receptor for rab5-GDP and participate inthe activation of rab5 [1].