Ipl1p-dependent phosphorylation of Mad3p is required for the spindle checkpoint response to lack of tension at kinetochores.
The spindle checkpoint delays anaphase onset until all chromosomes are correctly attached to microtubules. Ipl1 protein kinase (Aurora B) is required to correct inappropriate kinetochore-microtubule attachments and for the response to lack of tension between sister kinetochores. Here we identify residues in the checkpoint protein Mad3p that are phosphorylated by Ipl1p. When phosphorylation of Mad3p at two sites is prevented, the cell's response to reduced kinetochore tension is dramatically curtailed. Our data provide strong evidence for a distinct checkpoint pathway responding to lack of sister kinetochore tension, in which Ipl1p-dependent phosphorylation of Mad3p is a key step.
King
Emma M J
EM
Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom.
Rachidi
Najma
N
Morrice
Nick
N
Hardwick
Kevin G
KG
Stark
Michael J R
MJ
D064127:Aurora Kinases; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D018816:Genes, cdc / Q000502:physiology*; D007150:Immunohistochemistry; D018386:Kinetochores / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D008941:Spindle Apparatus / Q000378:metabolism*; D015003:Yeasts
D018797:Cell Cycle Proteins; C406764:MAD3 protein, S cerevisiae; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases