Vesicular Transport Flashcards
what is biosynthethic-secretory pathway?
synthesize and you secrete it to where it needs to go
when is endocytic pathway?
endocyotosis, bringing things from outside
what is retrieval pathway?
makes sure membrane comes back
cargo ____ with the next membrane to get to its destination
merges
are all these membrane compartments the same or distinguishable from each other
distinguishable
what are markers?
membranes that mark compartments to maintain their uniqueness (PI, phosphoinositides, phosphoglyercide lipid)
how do vesicles form?
vesicles bud off of one compartment and merge with the target compartment
what are the 3 types of coated vesicles?
clathrin, COPI, COPII.
coated with proteins on cytosolic side.
what is the function of the protein coat of vesicles?
molding of vesicles, concentrating proteins you need to pinch off into vesicle
what are clathrins?
transport of vesicles from plasma membrane/golgi to endosomes
what is COPII?
transport ER to Golgi (start trans-golgi)
what is COPI?
transport from golgi (start CIS-GOLGI) towards ER
clathrins are composed of _____ shapes and have what chains?
triskelion and 3 heavy chains and 3 light. slightly curved to make 3D shape
what composes the outer shell of COPII?
sec 13/31
how does a membrane cargo grab onto a vesicle and go?
it has a site that will bind to coat assembly mechanism
how does a soluble cargo grab onto a vesicle and go?
it cant interact with co-protein mechanism so it binds to cargo receptor. and receptor binds with adapter and co-proteins
when does coat assembly happens?
only when its neeed
what is coat assembly triggered by?
coat-recruitment GTPases
what are the 2 coat-recruitment GTPases?
SAR1: COPII at the ER
Arf: interacts with COPI and clathrin at the Golgi
what happens after SAR1 GTP binds to membrane?
it is a binding site for the inner coat of COPII (Sec24 and Sec23). Sec 13/31 assemble on top and pulls membrane away.
how do vesicles pinch off?
dynamin squeezes the neck of vesicle so membrane is pinched off from donor membrane
what happens if theres a dynamin mutation?
neck will get really long but it will not pinch off
what happens after vesicle is pinched off?
coat proteins dissociate. proteins are recycled
what protein does vesicle targeting?
Rab protein
how does Rab work?
Rab is on vesicle and binds to its specific Rab effector on target membrane.
what protein does vesicle membrane fusion?
SNARE
how does SNARE work?
SNARE on vesicle (v-SNARE) and SNARE on target membrane (t-SNARE) twist around each other and membranes merge
how are SNAREs recycled?
proteins unwind the SNARE for reuse
what kind of proteins go from ER to golgi?
transmembrane proteins, secreted proteins (insulin),
what coat protein is for ER to Golgi (cis-golgi)?
COPII
what are exit signals?
tell vesicles to go another part
only proteins that are ______ folded can exit the ER
properly