Abstract
The spindle position checkpoint (SPC) ensures correct mitotic spindle position before allowing mitotic exit in the budding yeast Saccharomyces cerevisiae. In a candidate screen for checkpoint genes, we identified bud2Δ as deficient for the SPC. Bud2 is a GTPase activating protein (GAP), and the only known substrate of Bud2 was Rsr1/Bud1, a Ras-like GTPase and a central component of the bud-site-selection pathway. Mutants lacking Rsr1/Bud1 had no checkpoint defect, as did strains lacking and overexpressing Bud5, a guanine-nucleotide exchange factor (GEF) for Rsr1/Bud1. Thus, the checkpoint function of Bud2 is distinct from its role in bud site selection. The catalytic activity of the Bud2 GAP domain was required for the checkpoint, based on the failure of the known catalytic point mutant Bud2(R682A) to function in the checkpoint. Based on assays of heterozygous diploids, bud2(R682A), was dominant for loss of checkpoint but recessive for bud-site-selection failure, further indicating a separation of function. Tem1 is a Ras-like protein and is the critical regulator of mitotic exit, sitting atop the mitotic exit network (MEN). Tem1 is a likely target for Bud2, supported by genetic analyses that exclude other Ras-like proteins.
References
Jun 28, 1991·Cell·J ChantI Herskowitz
Jun 28, 1991·Cell·J Chant, I Herskowitz
Jan 1, 1989·Methods in Cell Biology·J R PringleE W Jones
Dec 1, 1989·Proceedings of the National Academy of Sciences of the United States of America·A Bender, J R Pringle
Nov 17, 1995·Science·T MorishitaY Anraku
May 1, 1995·The Journal of Cell Biology·J Chant, J R Pringle
Nov 1, 1993·Proceedings of the National Academy of Sciences of the United States of America·A Bender
Sep 16, 1993·Nature·H O ParkI Herskowitz
Apr 1, 1996·Molecular and Cellular Biology·J E ZahnerJ R Pringle
Jul 18, 1997·Science·K ScheffzekA Wittinghofer
Jun 23, 1997·FEBS Letters·A WittinghoferM R Ahmadian
Aug 13, 1999·Genes & Development·H O ParkI Herskowitz
Apr 21, 2001·Science·P J KangH O Park
May 30, 2001·Current Biology : CB·A L MarstonJ Chant
Jun 16, 2001·Molecular Biology of the Cell·J Ho, A Bretscher
Apr 18, 2003·Current Biology : CB·Guillaume A CastillonRichard A Heil-Chapdelaine
Jun 5, 2003·The Journal of Cell Biology·Satoshi YoshidaAkio Toh-e
Jul 2, 2003·Molecular and Cellular Biology·Allison J BardinAngelika Amon
Jan 28, 2005·Journal of Cell Science·Stephen M Huisman, Marisa Segal
May 27, 2005·Cell Cycle·Anupama Seshan, Angelika Amon
Jul 26, 2005·Molecular Cell·Gislene Pereira, Elmar Schiebel
Jul 26, 2005·Molecular Cell·Katharine E D'AquinoAngelika Amon
Jun 9, 2006·Cell Division·Simonetta PiattiRoberta Fraschini
Jul 7, 2007·Molecular Biology of the Cell·Scott A Nelson, John A Cooper
May 17, 2008·Biochemical Society Transactions·Roberta FraschiniSimonetta Piatti
Dec 2, 2009·The Journal of Cell Biology·Marco GeymonatSteven G Sedgwick
Jun 15, 2011·The Journal of Cell Biology·Daniela Trinca BertazziGislene Pereira