Ras And Rab Interactor 3 (RIN3)

RIN3 bound GTP preferentially over GDP and acted as a guanine nucleotide exchange factor on RAB5B. By immunostaining and confocal microscopy of RIN3 transiently expressed in HeLa cells, they colocalized RIN3 and RAB5 to punctate vesicles in the cytoplasm and found that vesicular localization of RIN3 required the RIN3 C-terminal region, suggesting that RIN3 binding to RAB5 is needed for vesicular localization. In HeLa cells expressing RIN3, transferrin (TF) was transported partly through RIN3-positive vesicles to early endosomes, suggesting that RIN3 plays a role in intracellular transport from plasma membranes to early endosomes. Yeast 2-hybrid analysis and GST pull-down assays showed that RIN3 interacted through its N-terminal PRDs with the SH3 domain of amphiphysin II (BIN1).