BIO 320 Lecture Notes - Lecture 35: Ndc80, Sister Chromatids, Laser Ablation
Document Summary
At kinetochores with insufficient tension, aurora-b kinase phosphorylates. Ndc80 complex (and other proteins) to cause detachment of microtubules from such kinetochores. Tension causes aurora-b kinase to be unable to reach its substrate proteins (e. g. , ndc80 complex) at the outer kinetochore: reduced affinity for, microtubule, (phosphate put on by aurora-b removed by phosphatase) Multiple forces move chromosomes to the metaphase plate. Proteins and forces at kinetochores during congression: At leading kinetochore: catastrophe factor; (-) end-directed motor. At lagging kinetochore: +tip that stabilizes growth; (+) end- directed motor. At both kinetochores: a means to maintain attachment when the microtubule end grows or shrinks (e. g. , involving motors and. The leading and lagging kinetochores must act coordinately. Chromokinesins (or kinesin-4, -10) are (+) end-directed motors that are bound along the chromosome arms. They provide polar (astral) ejection force that helps the sister chromatids align at the midpoint between the two poles (metaphase plate) Chromokinesins alone are not sufficient for congression.
