Term
| Ways to measure protein half-life |
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Definition
1. pulse chase analysis using radiolabeled cells
adds-met to cell growing in -met media
pulse for 1-15 min
chase (add ~10 to 100 fold unlabeled met)
IP protein and analyze in SDSPAGE 2. cyclohexamide chase protocol analyze by western **used for short lived proteins**
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Term
| Physiological significance of protein degredation |
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Definition
- destruction of abnormal proteins
- turnover of normal proteins
- regulated destruction of normal proteins
- Antigen Presentation CLass I and Class II
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Term
define lysosomes (also name its equal in yeast) |
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Definition
| an acidic organelle that contains proteases (cathepsins) and glycosideases with acid pH optimums |
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Term
| Name some lysosomal protease inhibitors which block protein turnover |
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Definition
lysosomotrophic amine=neutralizes pH of the lysosome and endosomes NEM=cysteine protease inhibitor, inactivates certain lysosomal proteases |
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Term
| what do NEM AND chloroquine NOT inhibit? |
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Definition
Class I antigen presentation destrcution of abnormal proteins turnover of normal proteins degredation of cyclins |
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Term
| how are lysosomes controlled? |
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Definition
| they only work at low pHs in the lysosome therefore if they were accidently released into the cytosol, they would be rindered ineffective becuase they would be at normal pH. |
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Term
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Definition
76 reside protein that is highly conserved. has 7 lysine residues poly-Ub chains linked through lysine 48 are the tag for protein degredation. Minimal length=4 |
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Term
| Name the steps for ubiquitin conjugation |
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Definition
step 1: conjugatable Ubl gets AMP attached step 2: the SH attachs the Ub molecule to specific enzyme step 3: this new cleavable bond is CLEAVED and TRANSFERED to the E2 complex. step 4: one of the two E3 complexes transfers the Ub onto the substrate step 5: de-ubiquinating enzymes cleave off the bond and thus Ubl is recycled.
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Term
| reaction involving the Ubiquitin activating enxzyme (E1) |
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Definition
Ub+E1+ATP --> AMP~Ub+PPi+E1 E1+AMP~ub--> E1-S~ub +AMP |
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Term
| Why are there multiple Ubcs? |
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Definition
partially overlapping functions independent functions-certain E2s interact with specific E3s Some Ubcs are involved in conjugation of proteins related to Ub. |
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Term
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Definition
cells contain many different E3s that belong to distinct protein families E3s are defined as enzymes that directly or indirectly MEDIATE THE TRANSFER of Ub from an E2 to an amino group in a protein substrate the C-terminal glycine residue of Ub is LINKED to the protein via an isopeptide bond |
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