Small GTPases of the rab family are involved in the regulation of vesicular transport. The restricted distribution of each of these proteins in mammalian cells has led to the suggestion that different rab proteins act at different steps of t ransport (Pryer, N. K., L. J. Wuestehube, and R. Scheckman. 1992. Annu Rev. Biochem. 61:471-516; Zerial, M., and H. Stenmark. 1993. Curr. Opin. Cell Biol. ...
