Two families of
GTPases, Arf and Ypt/rab, are key regulators of vesicular transport.
While Arf proteins are implicated in vesicle budding from the donor
compartment, Ypt/rab proteins are involved in the targeting of
vesicles to the acceptor compartment. Small GTPases are positively
regulated by factors that stimulate guanine nucleotide exchange,
GEFs. Recently, we have shown that the four known members of the
Sec7-domain family in yeast can function as Arf GEFs, and exhibit
distinct genetic interactions with exocytic YPT genes. The
interactions observed suggest the existence of Ypt-Arf GTPase cascade
that regulates the secretory pathway. The nature and the role of such
a cascade will be discussed. Supported by: NIH-GM-45444.
Return to YGM 2000 Abstract Index