Types Of Vesicle Transport And Lysosomes Flashcards
What are the three types of vesicles
Cop1 coated
Copll coated
Clathrin coated
What are cop 2 coated vesicles
They move cargo forward from the ER to the golgi
How do cop 2 vesicles actually collect the proteins to be transport from the ER
Cop ll select and concentrate certain protiens by interacting with transmembrane protiens that have ER export signals
What types of protiens do cop 2 vesicles actually select and concentrate
Enzymes destined for Golgi (ex glycosyltransferase)
Proteins involved in vesicle docking and fusion with things (ex SNARE)
Proteins that bind to soluble cargo (which is supposed to be secreted out of the cell)
What things are needed to form cop 2 vesicles
Sar 1 (g protien)
Sec 23/24
Sec 13/31
What are the first two steps in cop 2 vesicles forming
- Sar 1 (a cop 2 coat G protien)
Sar 1- GDP is recruited to the ER by guanine exchange factor (GEF) to turn its into. SAR 1 GTP
- SAR 1 GTP changes conformation to insert into the cytoplasmic leaflet of the ER memebrane (this bends the membrane to begin vesicle budding
What are the 3 and 4 steps in cop 2 vesicles forming
- Sec 23/24 dimer is recruited and further bends the membrane
The sec 24 portion is the primary adaptor protien that recruits protiens to the vesicle by interacting with the ER export signals of the ER membranes protiens
- Sec13/31 for an outer structural cage around the vesicle
What is the last (5th) step in cop 2 vesicles forming
After the vesicle has fully formed
The disassembly of everything is triggered by hydrolysis of the GTP on SAR 1 to GDP
What are the two major functions of cop 2 protiens
Bend the membrane
Select and concentrate protiens to be transported
What are cop 1 coated vesicles
They move cargo backward from either
ERGIC/GOLGI to the ER (we resident back to ER)
Or from trans to cis golgi
What is the cop 1 coat made of
It’s thick and made of a protien complex called a coatamer
This coatamer makes the thick protien coat on the membrane of the vesicle that’s forming
For cop 1 vesicles what protien bends the membrane to from the vesicle
Arf1 G protien
The GTP from of it binds to the membrane
How do the protiens get initiated to go back to the ER for cop 1 transport
The protiens that are meant to stay in the ER have a retrieval signal
The soluble ER protiens have the signal lys asp glu leu (KDEL) that’s recognized by the KDEL receptor
The ER membrane protiens have a
Retrieval signal of LYS LYS X X (KKXX)
Each compartment in the endo membrane system has its own retrieval signal
What is the KDEL receptor
It collect the soluble protiens to be shuttled between the cis golgi and the ER compartments
It interacts with the cop 1 coat which is on the cytosolic side of the vesicle to actually bring the soluble protiens back to the ER
What is the first step in vesicles fusing to something
- The vesicles move toward the specific target compartment
This movement is mediated by microtubules and motor protiens
What is the second step in vesicles fusing to something
- The vesicles are actually tethered to the target compartment through two types of tethering protiens:
A rod shaped fibrous (long) protien
A multiprotein complex (clump, brings closer)
RABS (g protien) is also involved
In step 2 of vesicle fusion what does the g protien RABS do
G protien RABS help determine specificity in two ways:
It recruited specific tethering protiens to the vesicle
It also interacts with specific motor protiens
What is step 3 in vesicle fusion
The vesicle are docked (brought to) the membrane of the target compartment
This is done by SNARE protiens the t snare and the V snare which are integral membrane protiens
They interact with each other to form 4 stranded bundles
What is the v snare and t snare
V snare is put inside the transport Vesicales during their intial budding
T snare is located in the Target membrane
What is step 4 of vesicle fusion
The vesicle fuses with the target membrane by tsnared and v snared interacting and pulling the lipid bi layer of the vesicles and target membrane together
This causes enough force for them to fuse
What things all contribute to the fusion of vesicles
RABS
Tethering protiens
SNARES
RAB protiens are ____
Master regulators of vesicle transport between compartments in cells
What are clathrin coated vesicles
They move materials from the trans golgi network (very top) to endosomes lysosomes and plant vacuoles
They also do endocytosis
When do lysosomes hydrolytic enzymes work best and how is their ph maintained
They have at least 50 hydrolytic enzymes and they have optimal activity at low (acidic) ph, ph of the lysosome is 4.6
They are acid hydrolases
The ph is maintained by a proton pump (ex. V type proton atp-ase)
