Term
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Definition
| Direct proteins to various organelles |
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Term
| Signal peptide can be ______ or ________ |
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Definition
Signal peptides; either at an end (N usually) or internal and heirarchical
OR
Form a signal patch based on 3-D structure |
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Term
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Definition
- K-D-E-L
- Lys-Asp-Glu-Leu
- Near Carboxy terminal |
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Term
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Definition
| - Long string of hydrophillic amino acids |
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Term
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Definition
1) Synth mem lipids for ER, Golgi, Lysosome, Plasma Mem, Mito, Peroxisome
2) Mem proteins of ER, Golgi, Lyso, PM
3) Synth resident prots of ER lumen, golgi, lyso
4) Secreted proteins delivered to ER lumen |
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Term
| Function of SER in All cells |
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Definition
1) Membrane lipids; phospholipids, cholest, ceramide
2) Stores Ca |
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Term
Specialized functions of SER
(Ledying cells/Hepatocytes/Muscles) |
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Definition
1) Steroid hormones in ACortex, Leydig-Testes, Granulosa ov
2. Hepatocyte; detox lip sol drugs + inducible
3. Muscle; sequester Ca |
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Term
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Definition
1) Synth protein eventually has ER signal sequence SRP
2) Signal recog protein (SRP recp) recogz and shuttles ribo to ER
3) Protein is translocated after ribo-srpr complex is docked then one transl resumes srpr is released and recycled |
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Term
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Definition
| Cleaves peptide from signal sequence so protein is released into lumen |
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Term
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Definition
- Single pass
- Coo faces cytosol
- Stop transfer protein |
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Term
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Definition
- Single pass
- Amino faces cytosol
- signal anchor protein |
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Term
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Definition
- signal anchor protein
- transmembrane
- COO faces cytosol |
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Term
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Definition
- Multipass protein
examples;
- G-protein receptors
- Glucose transporters |
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Term
| Co-translation modifications in RER |
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Definition
- N-linked glycol starts in RER
- Hydroxylation of lysine and proline in collagens
- Cleavages: signal pep remove sig sequence
- Conformational Changes
- Dimerization; oligomerization |
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Term
| Lumenal ER Protein return |
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Definition
- Contain KDEL or related seuquence
- Those that escape are returned using Kdel receptor
- Has higher affinity for KDEL protein in golgi environment than ER, so shuttles back to ER and lets go |
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Term
| BIP/Calnexin/Calreticulin |
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Definition
| - Chaprones that help protein properly fold before leaving RER |
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Term
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Definition
| - Protein disulfide isomerase catalyzses rearrangement of disulf bonds to achieve thermodynamically stable conformation |
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Term
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Definition
- Chaperone
- Binds to hydrophobic areas to prevent improper associations |
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Term
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Definition
- Membrane anchored
- Calnexin binds incomp folded protein with 1 terminal glucose on N-linked oligos
- Removal of gluc frees
- If protein misfolds glucosyl transferase adds a glucose
- Cycle repeats till proper folding |
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Term
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Definition
| - Similar to Calnexin but is not membrane bound |
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Term
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Definition
-ER-Associated degradtion
- Pathway for defective proteins
- Deglycosylated
- Trafficked by ubiquitin
- Translocated and degraded in proteosome |
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