BIOLOGY 2B03 Lecture Notes - Lecture 22: Wild Type, Chromatin, Intermediate Filament
Document Summary
A heterodimer of active cdk + cyclin (they make mpf) uses phosphoregulation to initiate the many important changes of mitosis, starting at prophase. In order to reverse these changes at the end of mitosis, mpf must be inactivated through ubiquitin-mediated degradation of cyclin b. Once mpf is inactive, cytosolic phosphatases can dephosphorylate the same key proteins that were phosphorylated before to reset it to interphase. Mpf triggers: mitotic spindle formation by phosphorylating mt associated proteins (maps) which cause instabilty of. Mt and centrosome separation: chromosome condensation through phosphorylation of. Condensins and histones: sister chromatid separation by phosphorylating. Cohesins so that separase can separate the sister chromatids this also contributes to condensation: nuclear envelope breakdown by phosphorylation of nuclear lamins, breakdown of golgi and er (endomembrane) by phosphorylating gm130. Progression and exit through mitosis, requires decrease in mitotic cyclins and. Also requires activity of phosphatases to dephosphorylate the proteins targeted by mpf.
