Lecture 11 Flashcards
What is the transport of the folded ER protein to the golgi mediated by?
transport vesicles that bud from the ER and fuse with the golgi
What forms membrane vesicles?
Formed by coat proteins
Where do COP proteins form the vesicle at?
At the ER and the Golgi
What are the two steps of vesicle formation?
- soluble ER proteins are sorted into forming vesicles by cargo receptors
- transmembrane proteins are sorted into vesicles by binding to coat proteins
How are vesicles fused with the golgi?
The ER derived vesicles uncoat, tether with the golgi, dock and fuse with the golgi
What are Rab proteins?
Small GTPases that act as regulators/switches
What acts as molecular switches?
small GTPases
What do Rab GTPases regulate?
regulation of membrane fusion
What do Sar 1 GTPases regulate?
ER vesicle formations
What is GEF?
Guanine nucleotide exchange factor
What is GAP
GTPase accelerating proteins
What do small GTPases NOT do?
- don’t hydrolyze GTP spontaneously
- Don’t exchange GDP with GTP without help (requires GAP and GEF)
What is V-SNARE connected to?
transport vesicle
What is T-SNARE connected to?
target membrane
What process drives membrane fusion?
docking
What are the functions of the golgi aparatus?
protein sorting
Where are proteins sent?
Other proteins are sent to the cell surface or endosomal system
Proteins that are supposed to remain in the ER are sent back to the ER
What is the role of the CIS side of the golgi?
Receives vesicles from the ER
What is the job of the trans side of the golgi?
Form transport vesicles that traffic to endosomes or the cell surface
What is the role of constructive secretion?
delivery of plasma membrane proteins
What is the role of regulation secretion?
secretion of regulatory proteins
Describe the regulated secretion of insulin … As glucose is increased, the ATP levels are increased which close ….
K+ channels, which causes depolarization of membrane potential, which opens Ca2+ channels, which triggor fusion of insuling - containing vesicles with the plasma membrane
What triggers a rapid fusion of vesicles with the plasma membrane?
Increase in calcium levels caused by an action potential
When are synaptic vesicles ready to fuse?
After docked and primed
What is the contact site between cell interior and exterior?
Plasma membrane
What functions are localized to the cell surface?
transport function and signaling
What happens in the absence of uracil?
Fur 4 localizes to the eisosomes
What are eisosomes?
long membrane furrows
What keeps the nutrient transporter in the inactive state?
gel like membrane of the eisosome
What does the fluidlike membrane allow for in the eisosome?
allows transporter to efficiently import nutrients
What happens during endocytosis?
- uptake of nutrients
- degradation of cell surface proteins/lipids
- cell signaling/communicating
- immune response
What happens during phagocytosis?
- engulfing large particles
- the membrane raps around the particle
What happens during pinocytosis?
- uptake of fluid filled vesicles formed by clathrin
What is clathrin?
Made of 2 types of proteins which assembles into a cage that deforms the membrane
What is clathrin mediated by?
endocytosis
Clathrin and adaptors function in what?
cargo selection
What does Low density lipoprotein (LDL) do?
Delivers cholesterol and fat to cells
Triacylglycerol and chlesterylester are what?
storage fats
Where does the LDL receptor shuttle?
Between cell surface, endosome and back to the cell surface
What are endosomes?
Are protein and lipid storing compartments of the endocytic system
What are early endosomes?
Receive endocytic vesicles and recyle part of the material back to the cell surface
What is the role of lysosome/vacuoles?
a storage compartment for salts and amino acids
acidic compartment with enzymes to degrade macromolecules
What are late endosomes (MVB)?
package membrane and proteins into the lumen of the compartment and deliver their content to the lysosome for degradation
