BIO 320 Lecture Notes - Lecture 31: Cdc20, Nuclear Membrane, Nuclear Lamina
Document Summary
Nuclear lamin polymerizes to form the nuclear lamina, which provides structural integrity to the nuclear envelope. Phosphorylation of nuclear lamin by m-cdk causes depolymerization of nuclear lamin and nuclear envelope breakdown near the onset of. Negative feedback loops ensure timely exit from m phase. M-cdk activation leads to its own inactivation: M-cdk phosphorylates inactive apc/c to allow its activation through binding of cdc20. Exit from m phase when proteins previously phosphorylated to m-cyclin degradation. by m-cdk become dephosphorylated by different protein phosphatases (some of which are inactivated by m-cdk) In most cell types, there are actually two forms of apc: apccdc20 and. Apccdh1 (labelled as cdc20-apc and cdh1-apc in graph here). They differ in a single subunit: cdc20 vs. cdh1. Both poly-ubiquitinate phosphorylated m-cyclin (and many other proteins, including s-cyclin), leading to degradation of. M-cdk phosphorylates apccdc20 and activates it (by recruiting. Cdc20), whereas m-cdk (as well as g1/s- and s-cdk later on) phosphorylates apccdh1 and inactivates it (by preventing.
