BIO130H1 Lecture 6: Lecture 6.docx
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BIO130H1 Full Course Notes
Verified Note
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Document Summary
Many proteins need to enter er for modification w/ sugars. This occurs at same time they are being synthesized by ribosomes. Translation begins w/ synthesis of short signal peptide sequence, a signal recognition particle, protein complex binds to peptide which translation continues. Srp then binds to receptor in er membrane anchoring ribosome which binds its receptor and the signal peptide meets the translocator. The signal peptidase cleaves the signal peptide leaving the new protein molecule in lumen of er. Signal sequences are a stretch of aa seq of protein that directs protein to correct location in cell. In gene, located at beginning 5" end. A signal peptidase can remove signal from protein. Signal sequences can be internal stretches of aa which remain part of protein. Sorting of a secreted protein: translation starts on cytosolic ribosomes, signal sequence at amino terminal end directs protein to er, the signal sequence is hydrophobic it interacts w/ translocator.
