<p>This family consists of several Rab5-interacting protein (RIP5 or Rab5ip) sequences. The ras-related GTPase rab5 is rate-limiting for homotypic early endosome fusion. Rab5ip represents a novel rab5 interacting protein that may function on endocytic vesicles as a receptor for rab5-GDP and participate in the activation of rab5 [<cite idref="PUB00012981"/>].</p>