RAB PROTEINS

Rab proteins form the largest branch of the Ras superfamily of GTPases . They are localized to the cytoplasmic face of organelles and vesicle s involved in the biosynthetic/secretory and endocytic pathways in euk aryotic cells. It is now well established that Rab proteins play an es sential role in the processes that underlie the targeting and fusion o f transport vesicles with their appropriate acceptor membranes. Howeve r, the recent discovery of several putative Rab effecters, which are n ot related to each other and which fulfil diverse functions, suggests a more complex role for Rab proteins. At least two Rab proteins act at the level of the Golgi apparatus. Rab1 and its yeast counterpart Ypt1 control transport events through early Golgi compartments. Work from our laboratory points out a role for Ra66 in intra-Golgi transport, li kely in a retrograde direction. (C) 1998 Elsevier Science B.V. All rig hts reserved.