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99 Cards in this Set
- Front
- Back
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Cells sort proteins to their correct locations by _ _ (bound) and _ _ (free).
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secretory pathway
soluble ribosomes |
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Protein sorting via secretory pathway which is bound involves: (5)
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PM proteins
ER Golgi complex lysosomes secreted and extra-cellular matrix |
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Protein sorting via soluble (free) ribosomes involves: (4)
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nuclear proteins
chloroplast mitochondrial proteins peroxisomes |
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Fig 13.1 Overview of protein-sorting pathway:
mRNA with ER signal sequence sent _ _ _ then to Golgi Complex then either to _ _ or _. |
rough ER
PM lysosome |
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Fig 13.1 Overview of protein-sorting pathway:
mRNA translated by ribosome in cytosol either made into a protein or has target sequence and sent to _ if in an animal cell, _ if in a plant, _ to be digested, or _ to make more mRNA |
mitochondrion
chloroplast peroxisome nucleus |
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In secretory pathway, the protein is _ and _-_ (unfolded state) as it enters the ER
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nascent
co-translational |
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In secretory pathway, proteins are designed for _ will enter the lumen of ER
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secretion
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_ _ _ is a series of flattened membranous sacs that lie in layers. Secretary proteins are synthesized by _ _ to the ER lumen and have a signal sequence on their _ _ end.
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rough ER
surface ribosomes amino terminal |
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Signal of secretory proteins are _ and _ for ER targeting
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necessary
efficient |
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ER membrane must be present during protein synthesis in order for protein to _ which is a co-translational transport
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translocate
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Cotranslational transport of protein must have a _ to remove signal sequence. fig 13.4b
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microsome
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Ribosomes on ER do/don't have a signal to direct them to ER and are exact same are free ribosomes.
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don't
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All cells secrete some proteins. e.g. extracellular matrix proteins secrete: (3)
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collagen
fibronectin proteoglycans |
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All cells secrete some proteins and some are specifically designed to make ample amts like:
- _ that make albumin and transferrin - _ _ _ that make digestive enzymes |
hepatocytes
pancreatic acinar cells |
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Overview of secretory pathway: fig. 14.1
1. _-_ _ of proteins into or across ER. 2 transport of _ either fuse with _-Golgi or form a _-Golgi _. 3 _ movement of vesicles back to ER 4 _ migration (progression) where layers mature and move towards _ region (Antigrade) |
1co-translational transport
2vesicles, cis, cis, reticulum 3retrograde 4cisternal, trans |
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Cisternal Migration involves a _-golgi stack that moves to _ position then to the trans position.
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cis
medial |
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Cisternal Migration has _ _ that constantly move membrane back to keep golgi-resident proteins localized to cis, medial, and trans positions
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retrograde vesicles
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Cisternal Migration has _ _ move outward to the trans-golgi reticulum
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secretory proteins
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Cisternal Migration: at the trans-golgi reticulum, sorts secretory proteins into 2 possible pathways:
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1constitutive (continuous) secretion pathway aka exocytosis
2stored secretory vesicles |
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Cisternal Migration: Constitutive secretion pathway involves secretory vesicles fuse immediately with _ _. e.g. collagen in fibroblasts and serum proteins in hepatocytes
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plasma membrane
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Cisternal Migration: Stored secretion pathway is _ secretion (neuronal and hormonal) e.g. pancreatic acinar cells to secrete precursors for digestive enzymes (2) and pancreatic peptide hormones (2)
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regulated
trypsin, chymotrysin insulin, glucagon |
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Cisternal Migration: Stored secretion pathway regulates the release of proteins by _ _ with the release of Ca2+ into cytosol
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signal transduction
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Yeast used to genetically define the secretory pathway and has mutations (5 classes) called _ which are _-sensitive. fig 14.4
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sec
temperature |
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Also yeast sec mutants determine mutants in which stage...
_ to A to _ to B to _ to C- _-to-_ _ to D to _ _ to E to _ _ |
cytosol
rER rER-to-golgi vesicles golgi cisternae secretory vesicles exocytosis |
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Translocation of Secretory Proteins across ER begins in _ and has a _ _ _ at the _ terminus.
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cytosol
ER signal sequence amino |
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Translocation of Secretory Protein across ER:
signal sequence directs to _ on ER and ALSO directs transport of _ _ across the ER membrane |
ribosome
nascent protein |
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Translocation of Secretory Protein across ER: signal sequence has one or more _ (+ charged) AAs with several _ AAs.
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basic
hydrophobic |
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Translocation of Secretory Protein across ER's signal sequence has a basic + charged AA is critical bc is abolishes _ and the hydrophobic residues bind to _ _ _.
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targeting
Signal Recognition Particle |
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Translocation of Secretory Protein across ER: bidns to Signal Recognition Particle and tranferred to cytosolic protein can then move protein to _ _
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ER
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Translocation of Secretory Protein across ER: Signal Recognition Particle is a _ complex that is assembled in the _ and binds to signal sequence and the large ribo subunit (_)
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cytosolic
nucleolus LSU |
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Translocation of Secretory Protein across ER: Signal Recognition Particle is a _ and _ complex and has a P54 or _ nucleotide binding protein
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protein
RNA guanine |
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Translocation of Secretory Protein across ER: Signal Recognition Particle fig 13.5 can be used to block further _ in absence of microsome
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translation
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Translocation of Secretory Protein across ER: Signal Recognition Particle works with its receptor in _-_ _ with energy from _.
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co-translational transport
GTP |
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Translocation of Secretory Protein across ER: Signal Recognition Particle binds both _ _ and _ and stops further translation untril it interacts with _ by GTP hydrolysis. fig 13.6
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signal sequence
ribosome translocon |
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Co-transitional Translocation of Secretory Protein needs a translocon to bind with _ and _ _ to initiate translocation then _ and _ _ are transferred to the translocon
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SRP
SRP receptor ribosome nascent chain |
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Co-transitional Translocation: Translocon is a set of trans-membrane proteins that form a _ throught the ER membrane so chain passed through it and growing chain is never exposed to _. Chain _ w/n the ER lumen.
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channel
cytosol folds |
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Co-transitional Translocation: Translocon has many _ complexes to bind to LSU. The complex forms a _ _ on translocon
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Sec61
closed gate |
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Co-transitional Translocation: Translocon hydrolyzes GTP in both _ and _ _. fig 13.6
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SRP
SRP receptor |
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Insertion of Membrane Proteins: those that are in the plasma, ER, golgi, lysosome membranes are made in the _ _ _ and use secretory pathway. _ of protein w/n membrane determined while in rER.
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rER
orientation |
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Insertion of Membrane Proteins: Type 1 in ER lumen has _ _ _ on N-terminus. Type 2 doesn't have a signal sequence and has the N-terminus on the _ face. Type 3 have same orientation as Type #_ but no cleavable sequence. Type 4 have 2 or more _-_ _ aka multipass proteins
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cleaved signal sequence
cytosolic face 1 membrane-spanning segments |
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_ _ determine protein orientation w/n the membrane and are up to 25AAs long. Membrane proteins can have either terminal in _ or _, have 1 or more _ _-_, have an odd or even number of _ _-_. fig 13.10
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topogenic sequences
exoplasm or cytoplasm transmembrane alpha-helices transmembrane alpha-helices |
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_-_ _ (STA) serves as a membrane anchor that becomes a trans-membrane alpha helix which moves _ of translocon. e.g. insulin receptor fig 13.11
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Stop-transfer anchor
laterally |
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Proteins with opposite orientation in ER membrane: N-terminus on cytoplasmic side or C-terminus on lumenal side will have a single _ _ _ sequence that is NOT cleaved with _ charge on cytosolic side AKA Type #_
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internal signal-anchor (SA)
positive type 2 |
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Proteins with opposite orientation in ER membrane: N-terminus on lumenal side or C-terminus on cytoplasmic side will have a single _ _ _ sequence that is NOT cleaved with _ charge on cytosolic side AKA Type #_
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internal signal-anchor (SA)
positive type 3 |
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Proteins orientation in ER membrane: SA sequences general rule: flanking sequences that has the most _ AAs remain on cytoplasmic side
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basic
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STA is _ _ _ and SA is _ _ _-_
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stop-transfer anchor
single internal anchor-sequence |
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Type IV: Multipass Proteins: have multiple _ sequences containing alpha helices and is common for _ _, _, etc
The SRP interacts with the first helix (_) and in later helices doesnt play a role but _ is still involved. fig 13.13 |
topogenic
ion channels GPCRs SA translocon |
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STA is anchors to ER membrane and rewraps back in or ends with C-terminus in _.
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cytoplasm
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ER membrane proteins: Instead of alpha helix some use membranes by _ _ (_) like with Type #_with cleaved N-terminus fig 13.14ab
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Glycophosphatidly inositol (GPi)
type 1 |
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ER membrane proteins: GPI: _ cleaves the protein and transfers the lumenal portion of GPI
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endoprotease
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ER membrane proteins: GPI: Cells do this to get rid of _ part that may encounter the cytoskeleton and can move more freely. GPI targets certain regions.
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cytosolic
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_ _ of the primary AA sequence of about 20 AAs have hydrophobic blocks of AAs that appear as peaks above ZERO which allows you to predict _ _. fig 13.15a
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hydropathy profiles
topogenic sequences |
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Posttranslational Modifications and Quality Control: (4)
1. _ _ formation bn cysteines in the ER 2. Protein _ 3. Proper _ of proteins in the ER 4. Quality control of _-_ proteins |
1. disulfide bond
2. Glycosylation 3. folding 4. mis-folded |
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Posttranslational Modifications and Quality Control:Disulfide bond forms bn _. Cys-S-S-Cys which is an _. The bonds form as protein elongates and enters ER lumen and begins to _. The bonds stabilize _ and _ structure.
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cysteines
oxidation fold tertiary and quaternary |
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Posttranslational Modifications and Quality Control:Disulfide bond bn Cysteines uses what to make bond?
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PDI Protein disulfide isomerase
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Posttranslational Modifications and Quality Control:Rotation bn cis and trans around _-_ bonds in which _ kinks the peptide backbone so can be cis or trans. Its a _ _ unless accelerated by protein.
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peptidyl-prolyl
proline slow isomerization |
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Posttranslational Modifications and Quality Control: Rotation bn cis and trans uses what to make bond?
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PPI peptidyl-prolyl isomerase
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Posttranslational Modifications and Quality Control:Protein Glycosylaton is the principal modification that occurs on _ _ and _ domains of PM proteins. _ begins in the ER and is completed in the Golgi.
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secretory proteins
extracellular glycosylation |
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Posttranslational Modifications and Quality Control:Protein Glycosylaton has two general categories which are: fig 13.16
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O-linked and N-linked glycosylation
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Posttranslational Modifications and Quality Control:Protein O-linked Glycosylaton uses a _ (GalNAc) and is linked to the _ group of Ser or Thr. It usually adds _ oligosaccharides chains (1-4 sugars) each is addedone at a time.
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N-Acetylgalactosamine
hydroxyl short |
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Posttranslational Modifications and Quality Control:Protein N-linked Glycosylaton via _ (GlcNAc) and is linked to the _ _ of Asn. It has much larger chains containing _ which tend to branch. _ oligosaccarides are added initially then trimmed and modified.
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N-Acetylglucosamine
amide nitrogen mannose large |
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Posttranslational Modifications and Quality Control:Protein Glycosylaton uses precursors to the oligosaccharides which consist of nucleoside _- and _ sugars, made in the _ from NTPs and sugars, and uses _ linkage bn sugar and P has _ _.
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mono- and diphosphate
cytoplasm ester high energy |
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Posttranslational Modifications and Quality Control:Protein Glycosylaton: fig 13.17 Biosynthesis of dolichol pyrophosphoryl oligosaccharide percursors for 14 linked sugars process:
1 In _ the dolichol phosphate has a phosphate added by _ along with N-Acetylglucosamine. #_ are added. 2GDP adds 5 _. 3precuror is flipped into _ _ _. 4more mannose is added and precursor is completed. |
1cytosol, UDP, 2
2mannose 3ER lumen |
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Posttranslational Modifications and Quality Control:Protein N-linked Glycosylaton: fig 13.18 transfer of oligosaccharide to growing _ chain followed by initial _.
1 (Glu)3(Man)9(GlucNAc)2 attaches with ribosome and protein strand 2 _ are trimmed overtime 3 Ribosome disconnects 4 #_ _ is removed then sent to cis-golgi |
peptide
trimming 2glucose 4 one mannose |
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Posttranslational Modifications and Quality Control: Proper folding of proteins in ER: e.g. (_) and the chaperone (_) is used in the ER lumen
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PDI
BiP/Hsc70 |
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Posttranslational Modifications and Quality Control: Proper folding of proteins in ER: _ are a type of chaperone that binds sugars and 2 examples are: _ (intergral membrane protein) and _ (soluble protein). Also PPI is used. fig 13.20
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lectins
calnexin calreticulin |
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Posttranslational Modifications and Quality Control: Assembly of multimeric proteins aka _ or _ proteins deals with the _ structure and this is a main function of the _ _.
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secretory
membrane quaternary ER |
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Posttranslational Modifications and Quality Control: Assembly of multimeric proteins e.g.
_ with 2 heavy chains and two light chains linked with disulfide bonds. _ _ _ protein |
immunoglobins
influenza's trimeric HA |
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Posttranslational Modifications and Quality Control for mis-folded proteins, these won't move in the _ and remain bound to ER _ like BiP/Hsc70 or calnexin.
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golgi
chaperones |
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Posttranslational Modifications and Quality Control for mis-folded proteins: The unfolded proteins invoke a response and sent back to _.
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cytosol
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Posttranslational Modifications and Quality Control for mis-folded proteins. The induced "unfolded protein response" in ER fig 13.21
1 _ is an ER trans-membrane protein which binds to _ from lumen 2 membrane protein then _ and acts as a endonuclease to but _ mRNA 3The cut pieces is spliced in the _. 4 _ occurs inducing the transcription factors of HAC1 fig 13.21 |
1 IRE1, BiP
2 dimerizes,HAC1 3cytosol 4 translation |
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Posttranslational Modifications and Quality Control for mis-folded proteins. The induced "unfolded protein response" in ER and after the induced "unfolded protein response" the protein is sent back to cytosol and fed through the _ which degrades it by the _/_ pathway.
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translocon
ubiquitin/proteosome |
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Review Table 13.1...not sure what is important
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ER, Mito, Chlorop have sequence on N-terminus which is removed
Peroxisomes (matrix) and nucleus (nucleoplasm) have sequence on either C- or N-terminus and do not remove sequence |
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Proteins are post-translationally imported into _, _, _, and _. FYI rER import is _-_
fig 13.22 |
mito
chlorop peroxis nuclei co-translational |
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Mitochondrial import uses _-terminal signal, _, and _.
2 Translocons used are: _ - on outer membrane associates with outer membrane import receptor _- on inner membrane fig 13.23 The translocons want to move protein to _ _, _ space, _ and _ membrane |
N
translocons chaperones Tom Tim mitochondrial matrix, intermembrane, inner and outer |
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Mitochondrial import translocons use 3 types of energy:
cystolic _ (ATP) Matrix _ (ATP) _ _ (inner membrane) fig 13.23 |
Hsc70
Hsc70 H+ gradient |
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Mitochondrial import unfolded proteins using a cystolic _ by adding N-terminal matrix-targeting signal to target it to _ _ then targeting sequence is CLEAVED. _ can prevent unfolding and stops import. fig 13.24
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DHFR
mito matrix methotrexate |
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Mitochondrial import is complex fig 13.25
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dif signal sequences are used in dif pathways
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Chloroplast sorting/import is similar to mitochondrial but uses the translocons:
_- on outer chloro membrane _- on inner chloro membrane |
Toc
Tic |
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Chloroplast sorting/import has destinations to the _ and _, intermembrane space, and inner and outer membrane. Thylakoid are the site of _
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stroma
thylakoid photosynthesis |
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Chloroplast sorting/import is similar to mitochondrial but uses the translocons to go to thylakoids for _/_ is related to bacterial mechanisms.
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targeting/transport
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Folded proteins can be imported into _. The signal sequence is _-terminal and is/isn't cleaved off during or after transport. fig 13.29
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peroxisomes
C isn't |
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Proteins that are folded can be imported into peroxisomes process: fig 13.29
1 PTS1 target sequence is taken up by _ receptor 2 complex binds with trans-membrane protein in _ and protein is sent into matrix. |
1Pex5
2peroxisome |
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_ _ target proteins to the peroxisomal matrix vs membrane. It is dif than ER, mito, and chloro.
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different pathways
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Dif pathways target proteins to the peroxisomal matrix vs membrane: fig 13.30
PMP70 and catalase in perox in _ cells. Pex12 mutant cannot target matrix proteins but can target _ proteins. Pex3 mutants cannot target membrane proteins and thus _ proteins but you need membrane first |
wildtype
membrane matrix |
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Peroxisome biogenesis and divison: Zellweger Syndrome: fig 13.31 involves a defect in the peroxisomal _ _. This impairs _ function and lead to death. There are multiple types of mutations.
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protein import
organ |
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Identify parts of nuclear transport for proteins on slide 67 in ch 13
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cytosolic fibril
annular subunit lumenal subunit colunm, ring subunit nuclear fibril |
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The Nuclear Pore Complex (NPC): know parts in figure 13.32
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cytoplasmic side- cytoplasmic filaments, proximal filaments, cytoplasmic ring
lumenal area- spoke, central transporter nucleoplasm side- inner spoke ring, nucleoplasmic ring, nuclear basket |
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The Nuclear Pore Complex (NPC): filaments connected by a _ to form a basket on nuclear side which is attached to the nuclear _. There is a _ _ with proximal filaments and 8 spokes radiating from the central plug. Small items can diffuse through but larger particles need to be _ _.
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ring
lamina central plug actively transported |
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Nuclear Import: _ _ _ (_) is found in most karyophilic proteins which are synthesized in the cytoplasm but imported into the nucleus. First seen in _ _-#_ large T-antigen which does/doesn't enter the nucleus.
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Nuclear Localization Signal (NLS)
Simian Virus 40 (SVM 40) doesn't |
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Protein Nuclear Transport invloves the _ cycle with is similar to G protein cycles and uses _ and _ proteins. Ran-GDP is highest in _.
Ran-GTP is highest in _. |
Ran
GAP and GEF cytoplasm (GAP) nucleus (GEF) |
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Protein Nuclear Transport Process: fig 13.35
1 _ _ binds to NLS 2 _ _ binds to importin alpha. 3 there is a _ _, import via FG-repeat interactions. 4 In nucleoplasm, importin beta binds to _-_ and cargo is released. 5 alpha and beta return to cytoplasm and Ran-GTP is converted to Ran-GDP by _. |
1importin alpha
2importin beta 3conformational change 4Ran-GTP 5hydrolysis |
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Nuclear Localization Signal: in addition to the simple NLS found in SV40 large T antigen, there is a _ NLS that has 2 short basic sequences separated by about 10 AAs. e.g. is _.
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bipartile
nucleoplasmin |
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Nuclear Localization Signal: e.g. hnRNP A1 which has a _ NLS that overlaps with the _ _ _ (_). It uses a _ instead of reacting with importin alpha.
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hydrophobic
nuclear export signal (NES) transportin |
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Nuclear Localization Signal types:
(3) |
small
bipartite small nuclear RNAs (snRNAs) |
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Nuclear Localization Signal: Small nuclear RNAs of 4 which are transcribed by RNA Pol II so they have a _ _-_.
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U1, U2, U4, U5
5' g-cap |
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Nuclear Localization Signal: Small nuclear RNAs have a _ _ _ that helps export these to the cytoplasm and once there they can assemble proteins to form _. Also the cap is methlyated to make a _-_ _.
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cap binding complex
snurps tri-methyl cap |
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Nuclear Exportation Signal: Nuclear export process
1 Ran-GDP enters _ using importin. 2 GEF makes Ran-GDP into the Cargo complex that consists of _, _ , and _-_. 3 _ breaks down components to make _-_ 4 _ breaks down products |
1nucleoplasm
2NES, Exportin 1, Ran- 3GAP, Ran-GDP 4GAP |
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Nuclear Exportation Signal: export of _ is Ran-Independent but re-entering requires it.
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mRNAs
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