Protein Synthesis and Secretion Flashcards
What are the main functions of the SER?
1) Synthesis of lipids
2) Calcium Storage and Release
3) Glycogen Metabolism
4) Drug Detox
Where does synthesis of lipids occur specifically?
Cystolic side of the SER membrane (must be flipped to luminal side by flippases)
Where does phosphorylation of N-linked oligosaccharides occur?
cis Golgi network
Where does sulfation of N-linked oligosaccharides occur?
trans-golgi network on tyr residues
Where does modification and addition of N-linked oligosaccharides occur?
Golgi cisternae
What are the modification of N-linked oligosacchairdes?
1) Removal of Mannose
2) Addition of GlcNAx, Galactose, and Sialic Acid
Where are the enzymes that synthesize sphingomyelin and glycolipids from ceramide located?
Lumen of the golgi cisternae
Where are phospholipids, cholesterol, and ceramide synthesized?
Cystolic side of SER membranes
What are the 3 paths of secretion from the trans Golgi network?
1) Constitutive Secretion
2) Regulated Secretion
3) Lysosome Pathway
What is the default pathway (Golgi network secretion)
Constitutive Secretion
What is the name of the compartment that connects the RER with the cis Golgi network?
Tubular Vesicular Network aka TVN
What does the coated transport vesicle COP1 do?
RETROGRADE transport of vesicles
1) Tubular Vesicular Network to RER
2) Cis Golgi network to RER
3) Trans to Cis between cisternae of Golgi stack
What does the coated transport vesicle COPII do?
ANTEROGRADE Transport of Vesicles
1) Transitional RER to Tubular Vesicular network, or cis
2) Tubular vesicular network to cis golgi network
Where do clathrin-coated vesicles transport to?
Transport BOTH anterograde and retrograde between the trans-Golgi network and other cell compartments
What is Adaptor Protein (AP)?
The clathrin coat contains adaptor protein. It binds to the sorting signal of the protein & couples it to the protein coat of the budding transport vesicle
What is the role of ARF and Rab?
They regulate activity of adaptor proteins during coat formation.
What membrane GTPase is required to pinch off the budding transport vesicles?
Dynamin
Where does translation always begin?
Free ribosomes in the cytosol
The ER is continuous with the outer membrane of this structure?
The nuclear envelope
Are the lumens of the SER and RER continuous?
Yes
What is the main difference between RER and SER?
RER has bound ribosomes active in translation and SER has no ribosomes
What is the transport step, protein coat, and cargo protein for the KDEL signal sequence?
Retrograde, COPI, luminal RER
What is the transport step, protein coat, and cargo protein for the KKXX signal sequence?
Retrograde, COPI, and RER membrane
What is the transport step, protein coat, and cargo protein for the di-acidic (DXE) signal sequence?
Anterograde, COPII, and membrane and secreted;
X stands for any amino acid
What is the transport step, protein coat, and cargo protein for the mannose-6-P signal sequence?
Anterograde/Retrograde, Clatharin, and lysosomal
