Rab GTPases are critical regulators of membrane trafficking. The canonical view is that Rabs are soluble in their inactive GDP-bound form, and only upon activation and conversion to their GTP-bound state are they anchored to membranes through membrane insertion of a C-terminal prenyl group. Here we demonstrate that C-terminal prenylation is not required for Rab13 to associate with and traffic on vesicles. Instead, inactive Rab13 appears to associate with vesicles via protein-protein interactions. Only following activation does Rab13 associate with the plasma membrane, presumably with insertion of the C-terminal prenyl group into the membrane.
Keywords: DENN domain; DENND2B; GDI; GDP dissociation inhibitor; Rab; TI-VAMP; endosome; guanine nucleotide exchange factor (GEF); protein isoprenylation; vesicles.
© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.