Chapter 15 lecture - 1 Intracellular Compartments •...

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Unformatted text preview: 1 Intracellular Compartments • highly organized intracellular compartments • each has a unique identity of proteins, lipids (+/- glycoslyations) = function • each must grow, regenerate/divide, and maintain (turnover) • isolate components by differential centrifugation • specific molecular markers • working to understand: traffic patterns between components ID tags - protein sorting Part 1: protein sorting compartment ID tag Part 2: vesicular traffic protein & lipid membrane sorting exocytosis & endocytosis 2 genes in nucleus transcribed to mRNA translated into proteins using ribosomes in cytosol localize proteins to right location use ID TAG sequence on protein to localize and/or retain protein in right organelle genes in nucleus transcribed to mRNA translated into proteins using ribosomes in cytosol localize proteins to right location use ID TAG sequence on protein to localize and/or retain protein in right organelle Part 1: Protein Sorting: two general systems used in cell: DIRECT delivery from cytosol to organelle - the few INDIRECT delivery via vesicle trafficking (ER -- Golgi etc) – the many A brief look at Central Dogma (more later!) A close up of a molecular ID TAG: 15-60 aa stretches – in principle can considers actual sequence as well as general properties (e.g. hydrophobic, hydrophillic properties, basic, acidic Import to ER: N-met-met-ser-phe-val-ser- leu- leu-leu-val-gly-ile-leu-phe-trp- ala- thr- glu-ala-glu-leu-thr-lys-cyc-glu- val-phe-gln- etc Since translate protein on ribosomes the absence of a signal keeps it in cytosol. Since translate protein on ribosomes the absence of a signal keeps it in cytosol. MOST TAGS are BOTH necessary and sufficient for localization to organelle MOST TAGS are BOTH necessary and sufficient for localization to organelle 3 Either case need to have a molecular ID TAG: 15-60 aa stretches - both necessary and sufficient for localization to organelle considers actual sequence as well as general properties hydrophobic, hydrophillic properties i.e. stretches basic, acidic aa If remove ER tag, protein does not enter ER = tag is necessary . If remove ER tag, protein does not enter ER = tag is necessary . If place ER tag on cytosolic protein & it goes to ER = tag is sufficient . If place ER tag on cytosolic protein & it goes to ER = tag is sufficient . very large holes, proteins, ribosomes, mRNA, etc. go through in folded conformations (mitochondria, ER, peroxisomes) transport across membrane in unfolded state vesicles transport protein/lipids come to organelle via ER/Golgi membrane fusion Which is why Part 2: vesicle sorting is important. Three mechanisms of protein IMPORT: All mechanisms require Energy....
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This note was uploaded on 04/02/2008 for the course BIO 2600 taught by Professor Vanburkem during the Winter '08 term at Wayne State University.

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Chapter 15 lecture - 1 Intracellular Compartments •...

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