Markers and Random Proteins Flashcards
Sec 61 (marker for?)
rER
BIP
Chaperone in the ER lumen that loves unfolded proteins.
Overlap of transferrin and Opioid receptors
Early endosome
EGFR
Late Endosome
Acid Hydrolases (ex: phosphatase)
Lysosome
Atg9
Autophagy
PI(3)P
Endosomes
Sec 61
4 of them + associated proteins make the ER translocator
Sec 62/63
Associated with ER translocator. They recruit BIP which helps with post-translational translocation
PDI
Binds proteins to be retrotranslocated to break their bad disulphide bonds
PERK
UPR response (upregualate and activate chaperones, promote protein degradation, stop protein synthesis)
ATF6
UPR response (upregualate and activate chaperones, promote protein degradation, stop protein synthesis)
IRE1
UPR response (upregualate and activate chaperones, promote protein degradation, stop protein synthesis)
Dynamin
Wraps around neck of budding vesicle and then hydrolyses GTP to constict. May also recruit lipid modding enzymes to help with fusion
AP5
Involved in endosomal vesicular transport
Rab7
On retromer coats (bring MP6-R back to TGN)
ARF
Form COPI coat + golgi made clathrin coat
Sar1
Form COPII coat. Once activated, an ampiphillic alpha helix pops out and inserts into cytosolic leaflet. Then, it recruits coat-forming proteins.
Sec 23/24
Gather the cargo for COPII coats
Sec 13/31
Form the COPII outer shell
GDI
Binds inactive Rab to make it soluble in the cytosol.
GlcNAc
N-Acytylglucosamine
Calreticulum + Calnexin
Calcium activated lectins that bind sugars on proteins in the ER with only one glucose.
They help them associate with lectins chaperones that reduce cys residues, prevent aggregation and keep them from leaving the ER.
How is COPII dissembled?
Coat recruitment GTPases are always working towards hydrolyzing Sar 1 to make its tail pop out thus, vesicle only forms when it can outrun this.
HOWEVER
After vesicle formation, the coat is very strong without Sar 1 and will only dissemble after being phosphorylated by kinases on the target.
COPI however will just undo soon after pinching off.
How does clathrin uncoat?
PIP phosphatase was packaged in and it depletes the PIP that binds the adaptor.
Auxilin activates the ATPase activity of Hsp70 chaperones which use that energy to peel off the coat.
Mechs in place to ensure this doesn’t happen until the vesicle is done being made.
When vesicles pinch off which sides of the leaflets are brought together?
The two non-cytosolic sides
How does glycosylation work as a timer?
2 glucoses immediately cut off so calreticulum and calnexin bind. Cycle of unbinding and binding them until proper folding as last glucose removed and put back on.
During this, mannose is being trimmed and eventually will be recognized by retrotranslocator lectins. Thus must fold b4 time runs out.
What happens in each part of the Golgi?
CGN: sorting phosphorylation of lysosomal protein oligosacs
CC: Mannose removal
MC: Mannose removal + GluNAc added
TC: Sialic acid + Gal + NANA added
TGN: Sorting + sulfation of carbs and tyrosine residues + add gal + add sialic acid
What is the difference between high mannose and complex sugars. What determines what happens?
HM: nothing added after initial trim
Complex: add stuff after intiail trim
*Depends on where the sugars are in the protein and how accessible they are. to enzymes.
what are the 3 fates for proteins leaving golgi
secretory vesicles (regualted exocytosis)
direct to PM
lysosomes (if MP6)
what is a marker for recycling endosomes and early endosomes
transferin (holds Fe)
what is transcytosis?
movement from one side of membrane to another (endocytosis to early endosome to recycling endosome to PM)
ex: in babies binding to cargo receptor depends on the pH of each side of the epithelial cell
where do receptors go when they are done their job?
return to pm (without or with ligand)
ex: LDL-R and TFR+TF respectively
degraded ex: EGFR
trancytosed
what change as endosomes mature?
Rabs PIPs and SNARES
how are endosomes matured
V type ATPass lowers pH
intralumenal vesicles made to house receptors
TGN deliverd lysosomal proteins
how are intralumenal vesicle made?
patches of endosomal membrane invaginate into lumen and pinch off to form a multivesicular body.
this happens when multiple ubiquitin tags bind the cytosolic sodd of a cargo capture protein (or membrane cargo) .
then ESCRT proteins bind ubiquitin and PIPs and decide to defrom the membrane to make an internal vesicle.
t
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what is the endocytosis sorting station
early endosome
where do things go from early endosome
lysosome or recycled to PM
what are LDLs? How are they reglated by the cell?
BIG molecules that bring cholesterol into the cell. cells make more LDLR when they are low on cholesterol and they turn off its synthesis (along with cholesterol synthesis) when levels are high
how do LDLRs join clathrin coated pit?
diffuse across membrane till they see AP2 in a forming clathrin pit
what happens to LDL and LDLR after endocytosis
break up in early endosome
due to lower pH
LDL goes to lysosome and cholesterol ester is hydrolyxed to free the chloesterol
cholesterol used to make new membranes
LDLR recycled to PM
what kind of endocytosis makes big vesicles
phago
how do protozoa and euks used phago
proto: to eat
euk: to eat dead cells and invaders
what determines phago size
what it ate
what happens to things lysosome cant digest
become residual bodies that can be exocytosed
how does phago work
something binds receptors and then pseudopod extension forms
what is macropinocytosis
pinkcytosis triggered by receptors to form actun ruffles that make large fluid filled sacs. INC bulk fluid uptake x10
what is pinkcytosis
constitutive cell drinking that used short lived clathrin coated pits OR caveolae
what is I cell disease
mannose never phosphorylated in CGN so no MP6 and thus no acid hysrolases in lysosomes
where does mannose 6 P come from
add phosphorylated glucnac then cleave off the glucna so only phosphate on mannose
when do retromers assemble
cystoplamic tails of cargo receptors avalible
curved bilayer avalible
PI(3)P maker avalible
retromer stabilizes curvature after binding
what happens if m6p proteins are secreted on accident
M6PRs catch them with receptro mediated endocytosis
when do M6PRs bind and unbind
bind at 6.5 ph
unbind at 6
what vesicles carry mp6rs (coat type)
clathrin
what is autophagy
engulfing cytosol to get things in the cell too big for proteosome degradation system ex: dead organells
how are lysosomes made
late endosome fuses with preexisting lysosome
