GENE 540 Midterm: Proteolysis of Cyclins
Document Summary
The destruction box is recognized by enzymes which add ubiquitin molecules to lysines elsewhere in the cyclin protein. A ubiquitinated protein is targeted for degradation by a proteasome. The mitotic cyclins have a destruction box which targets them for ubiquitin- mediated proteolysis. Then the ubiquitinated mitotic cyclin protein gets destroyed by proteasome. The 19-s cap recognizes the poly-ubiquitin on a protein. Allows specificity for what to destroy and what not to destroy. The central cylinder 20s this is where the proteases are: proteasome ~ 1% of a cell"s proteins. 20s core multiprotein complex that forms a hollow cylinder: protease active sites are on the inside of the cylinder. 19s cap six subunit ring structure: recognizes targeted proteins (e. g. , polyubiquitinated proteins, the cap uses atp hydrolysis to unfold the target protein. The target protein is unfolded as it enters the cap and is cleaved as it passes through the. For the ubiquitin-mediated proteolysis there are 3 enzymes involved:
