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| Where are sugar modifications found on transmembrane proteins (outside of the plasma membrane or inside, lumenal side of Golgi or cytoplasmic side)? |
Glycosylated on the noncytoplasmic face (extracellular face) |
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mcs5109 Tue, 09 Feb 2010 03:10:41 GMT |
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| Does the ER lumenal or cytoplasmic portion of a protein destined for the plasma membrane end up on the cell surface? |
N-terminus in the ER lumen will end up on the cell surface |
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mcs5109 Tue, 09 Feb 2010 03:10:41 GMT |
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If I tell you that a protein is an integral membrane protein, but that no portion of the
polypeptide chain passes through the bilayer, how might this protein be imbedded in the
membrane? |
Covalently linked to other molecules that have a hydrophobic anchor in the bilayer |
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mcs5109 Tue, 09 Feb 2010 02:54:13 GMT |
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| How big would you expect these regions to be (how many amino acids should they span) for the hydrophobicity plot? |
~20ish aas |
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mcs5109 Tue, 09 Feb 2010 02:52:43 GMT |
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| Formation of the correct disulfide bonds occurs in the _____________ through the action of ____________. |
-lumen of the ER
-protein disulfide isomerase |
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mcs5109 Mon, 08 Feb 2010 08:32:59 GMT |
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reduction in the cytoplasm is achieved
primarily by _______________. |
glutathione,a tripeptide composed of
gamma-glutamyl-cysteinyl-glycine |
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mcs5109 Mon, 08 Feb 2010 08:32:59 GMT |
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| O-linked glycosylation |
on serine and threonine occurs in the Golgi |
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mcs5109 Mon, 08 Feb 2010 08:30:36 GMT |
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| N-linked glycosylation |
on asparagine in ER and then modified in the Golgi |
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mcs5109 Mon, 08 Feb 2010 08:30:36 GMT |
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| noncytoplasmic face info |
-extracellular face
-Glycosylated |
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mcs5109 Mon, 08 Feb 2010 08:29:49 GMT |
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| cytoplasmic face is the... |
lumenal |
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mcs5109 Mon, 08 Feb 2010 08:28:35 GMT |
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| ER protein destinations |
• N-terminus in the ER lumen will end up on the cell surface
• N-terminus in the cytoplasm will end up in the cytoplasm |
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mcs5109 Mon, 08 Feb 2010 08:28:35 GMT |
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| beta barrel structure |
-H bonding between peptide bonds of neighboring strands mask
hydrophilic residues |
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mcs5109 Mon, 08 Feb 2010 08:16:58 GMT |
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| Triton |
-dissolves membranes and solubilizes proteins by binding the membrane
associated region
-usually does not inactivate proteins |
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mcs5109 Mon, 08 Feb 2010 08:06:05 GMT |
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| SDS |
-denatures and separates subunits
-inactivates |
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mcs5109 Mon, 08 Feb 2010 08:06:05 GMT |
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| Detergents |
-amphipathic
-coat hydrophobic surfaces.
-ex: SDS and Triton X-100 |
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mcs5109 Mon, 08 Feb 2010 08:06:05 GMT |
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| Integral membrane proteins |
-require detergent to dissociate
-attached through some kind of hydrophobic connection with hydrophobic core of the bilayer
-Almost always composed of alpha helix that passes completely through the bilayer
-generally composed of hydrophobic amino acids to span the hydrophobic core of the bilayer
• Hydrogen bonding between neighboring peptide bonds
masks the hydrophilic parts so they can reside in the hydrophobic part of the bilayer
-or, can be covalently linked to other molecules that have a hydrophobic anchor in the bilayer |
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mcs5109 Mon, 08 Feb 2010 08:20:22 GMT |
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| Peripheral membrane proteins |
-dissociate with high salt or pH changes.
-ionic, not covalent, interactions |
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mcs5109 Mon, 08 Feb 2010 08:06:05 GMT |
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| inositol phospholipids |
involved in cell signaling |
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mcs5109 Mon, 08 Feb 2010 07:56:40 GMT |
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| Cholesterol |
• -OH is the polar head group
• only lipid that can spontaneously flip from one leaflet to another
• only in animal cells
• affects fluidity of membrane |
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mcs5109 Mon, 08 Feb 2010 07:56:40 GMT |
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| micelle |
-forms from lipid molecule with one fatty acid tail |
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mcs5109 Mon, 08 Feb 2010 07:56:40 GMT |
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| 4 major components of PM |
1. phosphatidylserine PS
2. phosphatidylethanolamine PE
3. phosphatidylcholine PC
4. sphingomyelin |
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mcs5109 Mon, 08 Feb 2010 07:51:31 GMT |
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| How thick is the bilayer? |
about 5 nm thick |
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mcs5109 Mon, 08 Feb 2010 07:51:31 GMT |
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| Prokaryote diameter |
1 to 10 microns |
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mcs5109 Mon, 08 Feb 2010 07:51:31 GMT |
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| Eukaryote diameter |
5 to 100 microns |
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mcs5109 Mon, 08 Feb 2010 07:51:30 GMT |
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