BIOL 1111 Lecture Notes - Lysosome, Covalent Bond, Half-Life
1 Feb 2013
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Document Summary
Chaperones: bind to and facilitate the correct fate of another protein chaperone binding can affect: folding assembly compartmentalization degradation. Hsp70 binding cycle: prevents aggregation: low affinity binding (hydrophobic stretch recognition) open , atp hydrolysis high affinity binding closed , adp removed chaperone disassociates. Hsp60: double doughnut structure very large (1/2 size of ribosome) central cavity provides shielded environment for folding. Hsp 90: conformational maturation of steroid hormone receptors and signaling kinases. **aggregation can cause disease by inducing conformational changes** Regulation: compartmentalization selective activation turnover is studied by pulse (5 minutes)-chase (hours); half-lives determined. Lipid degradation: glycerophospholipids can be degraded/remodeled throughout the cell sphingolipids centralized degradation (lysosome) cholesterol not degraded; its levels are regulated by controlling synthesis. Proteasome cytosolic degradation (as opposed to intra-organelle) 30% of newly made proteins fail to fold properly! 4 concentric rings + 2 caps (for regulation) complete proteasome = 26s inner rings (b-chains) contain proteolytic activity narrow entrance can"t insert folded proteins.
