BIOL 200 Lecture Notes - Lecture 33: Conformational Change, Mitosis, Dna Replication
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Topic 7. 1 cell cycle & checkpoints (continued) Maturation promoting factor (mpf: control entry into m-phase, located in the cytoplasm, positive regulator (i. e. its presence makes mitosis happen) Injection from a cell at one stage of cell cycle into a cell at another stage. When mpf was purified, it was found to contain a kinase. Kinase an enzyme that can phosphorylate target proteins using bound atp. Phosphorylation by kinases results in a conformational change. can either activate or inactivate the target. Mpf also contain another protein called cyclin which binds to cdk called a cyclin-cdk complex. The enzymatic unit: [cdk] remain constant throughout the cell cycle, but activity mimics [cyclin] The regulatory unit: [cyclin] cyclical build up during the cell cycle and crash to zero at the end of mitosis. Different cyclin/cdk pairs control entry into s-phase and into m-phase. Most eukaryotes have several cdks and cyclins controlling different aspects of the cell cycle.
