W4OutlineLec11 - Ribosome lines up with translocon pore The...

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Luis David Gomez 59866865 Bio 192 D103 Cell Biology Week 4 Lecture 11 Outline 2/ 1/08 Secreatory Pathway Protein import in the ER Why are there ribosomes on the ER? Sorting Signal for the ER signal is recognized by SRP-signal recognition particle binds to ribosome and translated protein, and STOPS translation SRP takes ribosome/protein complex to SRP Receptor (GTPases, act as GAP) Translocon opens once SRP is lost (translation starts again) Engergy of translation pushes protein into ER lumen as sorting signal enters lumen, the SORTING SIGNAL is removed SRP and its Receptor Hydrophobic sorting signal interacts with hydrophobic part of the receptor! Video-how does the ribosome sit on the translocon?
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Unformatted text preview: Ribosome lines up with translocon pore The ribosomes of the rER only translate proteins of the ER or secretary pathway Translocation —occurs co-translationally The translocon has many transmembrane domains, pore is not always open however we do not know how Proteins do not always need sorting signal to end up in ER however they do need a 20 AA hydrophobic domain Type 1- C terminus in Cytosol Type 2-C terminus in ER lumen Sequential Manipulations of a secratory pathway 1. Glycosilation- N-linked 2. Formation of S=S (disulfide) bridges 3. Oligomerization Protein Degradation by Proteosome--ubiquitin tags lable for breakdown serves as quality control...
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This note was uploaded on 05/28/2008 for the course BIOL D103 taught by Professor Suetterlin/macgregor during the Winter '08 term at UC Irvine.

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