Rab and ARF GTPase regulation of exocytosis.

Our understanding of the mechanisms governing of Rab and Arf protein function has exploded in recent years with a convergence of information from model genetic organisms, biochemical studies, cell biological observations and protein structural information. However, the list of known Rab and Arf interacting factors still remains small relative to the number of these small GTPases that have been identified through complete genomic sequencing. It can be anticipated that the factors listed and discussed in this review probably represent a small fraction of the Rab and Arf accessory molecules that remain to be discovered. The identification of regulators and accessory molecules for the Rab and Arf families has allowed investigators to elaborate themes and develop a framework for a mechanistic understanding of these proteins. The themes are highlighted in this review, which aims to concentrate on Rab and Arf function in exocytosis.