BIOC 212 Lecture Notes - Lecture 7: Garland Science, Glossary Of Ancient Roman Religion, Glycosylation
14 Oct 2015
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Document Summary
Proteins must be sorted during or after translation to their correct compartment or membrane. Sorting information is carried inside the proteins themselves. Smooth er: no ribosomes, sites of lipid synthesis. Secretory signal sequences have a typical pattern of amino acids: hydrophobic central region 8 or more residues long, with short polar regions on each side (some with charges and some not) flanked by short polar regions. In many cases, signal sequences are at the n-terminus: shorter hydrophobic regions (8-16 residues, often cleaved off after translocation. Signal sequence targeting: targeting steps, recognize a signal on a protein, energy of translation on ribosome drives polypeptide through the translocon. As ribosome makes a new protein keeps attaching a new amino acids through the trna and each amino acid gets pushed out produces energy. Ribosome exit tunnel: nascent polypeptides exit the ribosome through a tunnel in the large (60s) subunit, tunnel , neutral, polar, too small for tertiary folding, but secondary folding can occur.
