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Rho1p and Cdc42p act after Ypt7p to regulate vacuole docking
Author(s) -
Eitzen Gary,
Thorngren Naomi,
Wickner William
Publication year - 2001
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/20.20.5650
Subject(s) - biology , gtpase , vacuole , microbiology and biotechnology , bapta , rab , exocytosis , lipid bilayer fusion , biochemistry , cytoplasm , membrane , intracellular
Rho GTPases, which control polarized cell growth through cytoskeletal reorganization, have recently been implicated in the control of endo‐ and exocytosis. We now report that both Rho1p and Cdc42p have a direct role in mediating the docking stage of homotypic vacuole fusion. Vacuoles prepared from strains with temperature‐sensitive alleles of either Rho1p or Cdc42p are thermolabile for fusion. RhoGDI (Rdi1p), which extracts Rho1p and Cdc42p from the vacuole membrane, blocks vacuole fusion. The Rho GTPases can not fulfill their function as long as priming and Ypt7p‐dependent tethering are inhibited. However, reactions that are reversibly blocked after docking by the calcium chelator BAPTA have passed the point of sensitivity to Rdi1p. Extraction and removal of Ypt7p, Rho1p and Cdc42p from docked vacuoles (by Gdi1p, Gyp7p and Rdi1p) does not impede subsequent membrane fusion, which is still sensitive to GTPγS. Thus, multiple GTPases act in a defined sequence to regulate the docking steps of vacuole fusion.