BIO315H5 Lecture Notes - Lecture 19: Blastomere, Proteasome, Protein Kinase
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Explain figure 17. 10: two key components of the cell-cycle control system. When cyclin forms a complex with cdk, the protein kinase is activated to trigger specific cell cycle events. What are the enzymes that control cdk: cyclins, wee1: inhibitory kinase that phosphorylates active sites, cdc25: an activating phosphatase that undergoes wee1 action, cdk inhibitor proteins (ckis) that act as an inhibitory interactor that rearranges the active site. Explain figure 17. 13: the regulation of cdk activity by phosphorylation. The active cyclin-cdk complex is truned off when the kinase wee1 phosphorylates two closely spaced sites above the active site. Removal of these phosphates by the phosphatase cdc25 activates the cyclin-cdk complex. For simplicity, only one inhibitory phosphate is shown, cak adds the activating phosphate. Explain figure 17. 14: inhibition of a cyclin-cdk by a cki. This shows the structure of the human cyclin a-cdk2 complex bound to the cki p27.
