Lecture 13 11

Lecture 13 11 - Lecture 13 11/02/07 Golgi...

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Lecture 13 11/02/07 Golgi Structure/Function, Lysosome, Exocytosis Glycosylation Protects lysosome membrane proteins from autodegradation Transmembrane proteins in lysosome are highly glycosylated to protect them from degradation This acts as a barrier from luminal proteins of lysosome Applies to animal cells only Vacuole plants and fungi cells Functions in the regulation of cell size Pressure is maintained by vacuole o Turgor pressure (wilted plants have decreased Turgor pressure) o Proper osmotic pressure = proper Turgor pressure o If there is a drop in TP, vacuole can’t push against cell wall as it should Golgi Lysosome transport for proteins that function at Lysosome TGN: sorting center for proteins to go on to rest of cell o Proteins have a mark to designate them as lysosome destined proteins Manose 6 Phosphate = M6P Added to oligosaccharide sidechain Proteins with M6P mark are recognized as functional lysosomal proteins Recognition of Lysosomal proteins and transport 1.) Phosphotransferase- recognizes signal patch on lysosomal hydrolase -Add nacetyl glucosamine phosphate to manose on hydrolase -then trimmed by… 2.) Uncovering enzyme (UCE) -exposes Manose 6 P group -if the protein has multiple oligosaccharide sidechains, then it will have multiple M6P groups -more groups added more likely to be recognized, taken to lysosome M6P receptor (which recognizes M6P, transport protein to lysosome) requires higher pH to bind to protein with M6P mark o This is important so that proteins bind receptor at Golgi, but releases it at lysosome o pH of Golgi = 6 o pH of lysosome = 5 o pH of cytosol/ER = neutral Golgi Lysosome transport requires Clathrin Coat Another coat that causes a vesicle to form and bud off
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Lecture 13 11 - Lecture 13 11/02/07 Golgi...

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