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76 Cards in this Set
- Front
- Back
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What family of enzymes is so important in fatty acid metabolism in the ER? What important things can they do?
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cytochrome P450 family - including bile acid biosynthesis, cholesterol synthesis, etc.
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Why is cytochrome p450 important in pharmacology?
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It inactivates many important drugs.
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pore in ER membrane that pushes protein through as that protein is made
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translocon
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What is associated with translocon and ribosome receptor and helps dock it i guess?
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CRP receptor.
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What arrests the translation of a peptide until it sits on ER membrane (if it has the signal peptide)?
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CRP receptor (i think)
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For transmembrane proteins, what do they have that makes them clump in translocon of ER,
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stop sequence
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carboxy terminus of tarnsmembrane is in what in normal?
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the cytoplasm. The n terminus is in the lumen of the ER
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when you want amino terminus in cytosol for transmembrane spanning proteins, you do what?
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have the start sequence in the middle of the protein
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What proteins are extremely important in development? Where are they found
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GPI-linked proteins. Always in lumen of ER (or on cell surface)
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T/F - majority of glycosylation occurs CO-translationally.
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true.
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What are glycosylated, and what does the glycosylation?
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Only asparagines on the proteins are glycosylated, and it comes form a lipid-linked oligosacharide
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What is trimmed in glycosylation (in order)
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1) first, second, and third glucose individually
2) then you lose 1 manose (THIS marks the end of trimming in ER) |
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What is the mechansim ensured that only good proteins exit the ER?
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ERAD (ER-associated degredation)
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What allows the protein, after it is co-translationaly glycosylated, and it has a single glucose on it, to be folded properly?
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It binds to calnexin and calreticulin (chaperones that promote folding).
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What is the "sensor" of quality control?
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the glycosylating enzyme --> UGGT. It acts as folding center to know when protein is correctly folded
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What protein helps correctly folded proteins exit the ER?
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ERGIC-53
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At what point during glycosylation does a protein bind to calnexin and/or calretciulin?q
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When 2 of the 3 proteins have been trimmed away.
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Once a protien binds to chaperones calnexin and calreticulin, where does it go, to what protein?
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ERp57 - which helps it form disulfide bonds
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If a protein is misfolded, what reglucosylates it?
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glucosyl transferase (of UGGT)
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What does ERp57 do?
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It is a co-chaperon with calnexin (CNX) and calretciulin (CRT) and accelarates re-fodling and disulfdie bonds
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What are glycosylated, and what does the glycosylation?
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Only asparagines on the proteins are glycosylated, and it comes form a lipid-linked oligosacharide
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What is trimmed in glycosylation (in order)
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1) first, second, and third glucose individually
2) then you lose 1 manose (THIS marks the end of trimming in ER) |
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What is the mechansim ensured that only good proteins exit the ER?
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ERAD (ER-associated degredation)
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What allows the protein, after it is co-translationaly glycosylated, and it has a single glucose on it, to be folded properly?
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It binds to calnexin and calreticulin (chaperones that promote folding).
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What is the "sensor" of quality control?
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the glycosylating enzyme --> UGGT. It acts as folding center to know when protein is correctly folded
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What protein helps correctly folded proteins exit the ER?
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ERGIC-53
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At what point during glycosylation does a protein bind to calnexin and/or calretciulin?q
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When 2 of the 3 proteins have been trimmed away.
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Once a protien binds to chaperones calnexin and calreticulin, where does it go, to what protein?
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ERp57 - which helps it form disulfide bonds
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If a protein is misfolded, what reglucosylates it?
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glucosyl transferase (of UGGT)
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What does ERp57 do?
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It is a co-chaperon with calnexin (CNX) and calretciulin (CRT) and accelarates re-fodling and disulfdie bonds
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What trims the last glucose (last of 3) that signals a protein is folded correctly?
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Glucosidase II i thinik
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How do you get a protein out of ER?
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Through ER exit sites (ERES)
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how to proteins leave the ER at the exit sites?
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Via vesicles with COPII coats
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When leaving the ER in COPII coats, where do vesicles go?
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to vesicular tubular clusters - where they travel along microtubules
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protein pathway in golgi
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enter at cis
go through medial exit at trans |
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What stage of mitosis does the golig vesiculate?
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prophase
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what do you remove (sugar wise) in the golgi
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cis golgi - you remove mannoses and trim it to 5
later = add glucosmaine even later - take away more mannose. didn't get a great understanding of ths |
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where do O-linked glycosylation occur?
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in golgi, on threonines or serines. It is important for connective tissue proteins like GAG's to hold water
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for proteolytic processing in golgi, what cleaves positive arginine from albumin?
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furin
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explain how the mannose 6 phosphate signal works
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1) tagged in cis golgi with a phosphate at a mannose residue
2) in TGN, it interacts with specfiic receptor that moves it to late endosomes, which eventually becomes lysosomes |
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clatherine coats are associated with what?
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secretory granules in regulated secretory pathway
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Concentration of cargo in vesicles via clathrin that pinches off membrane form WHAT?
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secreotry granules that wait to be released
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How do you recycle vesicles so the golgi doesn't get huge and the ER doesn't get small?
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You get retrograde trafficking.
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What part of vesicular transport is very thrmodynamically unfavorable?
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fusion of lipid bilayer of vesicles to acceptor compartment.
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What proteins are key for budding?
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Coat proteins
Arf/Sar |
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the 3 coated vesicles that control trafficking?
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clathrin - secretory granules
copI - recycle membarne back copII - exit from ER - these all deform membrane to make bud, and select cargo |
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What protein families funciton as cargo recpeotrs?
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ERGIC-53 family - binds glycosylated cargo
p24 family - not as important, but still importnat Erv family - least conserved and we know least about |
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Sar1 and Secs23ect. are what?
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the GTPase that is involved in the coating of vesicles.
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What are somes disease of Sar1 and Sec?
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lose Sar1 - accumulation of chylomicrons in ER
sec23 - collagen trafficking misfunciton. or mutation in e-isoform is differnet disease. This demonstrates taht diff coats trafficks diff vesicles sec 24 - zebra fish problems, no idea why |
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How do you cut vesicle off membrane whne it buds off?
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Dynamin (of the GTPase family) that spirals around membrane bud and is a "pinchase" that pinches off vesicle
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the golig is one what end of microtubles?
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minus end (so vesicles move from plus to minus direction) via dyneins that move it in this direciton
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intitial recognition of vesicle with target membrane is thru what?
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tethers - like velcro, pulls vesicle towards it.
There are tethers in every step of secreotyr pathway |
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What od tethers work in conjunction with?
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Rabs
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what is the second layer of recognition
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T SNARE in target membarne
V SNARE in vessicle |
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How many snares come from vesicle/taget membarne?
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1 from vesicle
3 from target membrane bind to recognize vesicle |
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How do you separate 4-helix bundle of 1 V snare and 3 T snares?
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NSF - an ATPase that usesd ATP to dissociate snares so V snares can be recycled back to proximal compartment.
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what proteins faciliated fusion of bilayer of vesicle and target membrane ?
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predominaetly, it's the snares
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the acrosome reaction that allows sperm to penetrate the egg is through what?
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the secretory pathwa!
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What are the important phospholipids moieties made in the SER?
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1)Ethanlamine, serine, and choline are important head groups
2)Sphingosine is precursor to sphingomyelins (brain), and also form glycolipids 3)Galactocerebrosides and ganglioisides are important in development, infection 4)Also cholesterol |
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What do Cytochorome p450's do?
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- important in bile acid biosyntehsis
- lipid biosynthesis - steroid biosynthesis (from cholesterol precursor) -vitamin D metablosim -retinoic acid -prostacylcins/thrombaxanes A2 |
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What is the most common reaction of cytochrome p450?
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A monoxygenase reaction where an oxygen is inserted into organ substrate (RH) while other oxygen is reduced to water
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calnexin and clareticulin are located where?
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calnexin - lumen of ER
calreticulin - transmembrane in ER |
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what trims the mannose off in the golgi, and what does it take off exactly?
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mannosidase I and II (trim mannnose to 5, and then trimmed to 3
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What is used as a marker to track wehre proteins move through the golgi?
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endo H (bacterial glycosidase) because the glycogen chain is sensitive to this.
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Where does O linked gycoslylation occur?
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in golgi, on serine and threonine residues
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What is often cleaved from proteins in the golgi due to processing?
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Arginine is commonly cleaved in albumin and insulin
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explain in detail where lysosome tagging is done?
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- proteins are tagged on mannose with a phosphate in the cis golgi
- trans golgi, the M6P receptor interacts with protein and sends it to late endosomes, and eventaully lysosomes |
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What is dolichol?
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a isoprene in the ER membrane that transfers sugar onto proteins i believe
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What are the functions of coat proteins?
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1) deform membrane to bud off
2) select contents of vesicle |
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ERGIC-53
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transmembrane cargo receptor and a single spanning protein, with an N terminal domain in the ER that binds glyosylated cargo, and the other side (C-terminal?) that binds the coat
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The loss of what internal vesicle receptor causes bleeding diseases (?)
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ERGIC-53
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What is the order of coat binding on cop ii vesicles?
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1) Sar, which recruits sec 23-24
2) outer coat binds (sec13-31) |
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What causes cranio-lenticulo-satural dysplasia?
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a mutation in A isofrm of Sec 23, leads to collagen packaging defects and facial abnormalites (the B isoform causes something different).
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What energy does dynamin use?
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GTPase activity (so GTP)
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What does Botox and Tetanus toxin target?
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SNARES! That keep synaptic vesicles from fusing
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How are snares recycled?
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V-snare involved in fusion with COP II vesicles with the cis Golgi are recylcled back to ER in COP I vesicles
V snare invovled in fusing COP I vesicles with the ER is recycled back to golgi in Cop II |
