BUD2 encodes a GTPase-activating protein for Bud1/Rsr1 necessary for proper bud-site selection in yeast.
Cells of the budding yeast Saccharomyces cerevisiae bud at either axial or bipolar sites depending on their cell type. Bud-site selection directs both cell polarity and the cytoskeletal orientation during budding and is determined by at least five genes: BUD1/RSR1, BUD2, BUD3, BUD4 and BUD5. Mutants defective in BUD1, BUD2 or BUD5 choose bud sites randomly. Bud1 protein (Bud1p) has sequence similarity to Ras, a small GTP-binding protein, and Bud5p is similar to Cdc25p (refs 4, 5), a GDP-GTP exchange factor. Here we report that Bud2p is a GTPase-activating protein (GAP) for Bud1p with a sequence similar to the catalytic domain of rasGAPs, and that Bud2p purified from yeast stimulates GTP hydrolysis by Bud1p. Chromosomal deletion of BUD2 causes a random budding pattern but no obvious growth defect. Overexpression of BUD2 also causes a random budding pattern by wild-type cells.
Department of Biochemistry & Biophysics, University of California, San Francisco 94143-0448.
H O
HO
Park
J
J
Chant
I
I
Herskowitz
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004271:DNA, Fungal; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D020549:GTP Phosphohydrolase Activators; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D005800:Genes, Fungal; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
C083102:BUD2 protein, S cerevisiae; D004271:DNA, Fungal; D005656:Fungal Proteins; D020549:GTP Phosphohydrolase Activators; D020690:GTPase-Activating Proteins; D029701:Saccharomyces cerevisiae Proteins; D020558:GTP Phosphohydrolases