How do so few control so many?
The separation of sister chromatids at the metaphase-to-anaphase transition is triggered by a protease called separase that is activated by the destruction of an inhibitory chaperone (securin). This process is mediated by a ubiquitin protein ligase called the anaphase-promoting complex or cyclosome (APC/C), along with a protein called Cdc20. It is vital that separase not be activated before every single chromosome has been aligned on the mitotic spindle. Kinetochores that have not yet attached to microtubules catalyze the sequestration of Cdc20 by an inhibitor called Mad2. Recent experiments shed important insight into how Mad2 molecules bound to centromeres through their association with a protein called Mad1 might be transferred to Cdc20 and thereby inhibit securin's destruction.
Nasmyth
Kim
K
Research Institute of Molecular Pathology, Vienna, Austria.knasmyth@imp.univie.ac.at
D000705:Anaphase / Q000502:physiology; D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D020090:Chromosome Segregation / Q000502:physiology*; D010450:Endopeptidases / Q000378:metabolism*; D018386:Kinetochores / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008958:Models, Molecular; D009687:Nuclear Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D064249:Securin; D064247:Separase; D043743:Ubiquitin-Protein Ligase Complexes / Q000378:metabolism*
D018797:Cell Cycle Proteins; C501382:MAD1 protein, S cerevisiae; D009687:Nuclear Proteins; C578004:PDS1 protein, S cerevisiae; D010750:Phosphoproteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D064249:Securin; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D010450:Endopeptidases; C577986:ESP1 protein, S cerevisiae; D064247:Separase