TEST 3 TB Questions
Which coated vesicles move materials in a retrograde direction from the ERGIC and Golgi stack backwards toward the ER?
COPI coated vesicles
What mediates the interaction between membrane proteins and the COPII coat?
ER export signals in the cytosolic tails of integral ER membrane proteins
GTP binding proteins are also known as
G proteins
The interaction between the membrane of vesicles and their target compartment is mediated by which protein?
SNAREs
What GTP-binding protein plays a regulatory role in the formation and disassembly of the COPII coat?
SarI
vesicles that move through the cis-cisternae to the trans-cisternae are said to move in a _______ direction
antergrade
How are integral membrane proteins thought to enter the lipid bilayer?
aqueous translocon channel appears to have a gate that continuously opens and closes giving each nascent polypeptide segment a chance to partition itself into the lipid bilayer's hydrophobic core
How are G proteins help at the plasma membrane?
by covalent interactions with the lipid chains attached to the a alpha and gamma subunits
what is the name of the calcium-binding protein that acts in conjunction with calcium to bring about the responses associated with cytoplasmic rises of calcium ion concentration?
calmodulin
What happens if the UPR is unsuccessful in relieving the stressful conditions of the cell?
cell-death pathway is triggered
Lysosomal enzymes are transported from the TGN in vesicles coated with what protein?
clatharin
lysosomal enzymes are transported from the TGN in vesicles coated with what protein?
clatharin
What are the two sites within a cell where protein synthesis is generally thought to occur?
cytosolic surface of RER and free ribosomes
What determines the specificity of vesicle fusion to a target membrane?
interactions between specific combinations of interacting proteins, including tethering proteins, Rabs and SNAREs at that site in the cell
What are the recognition signals for lysosomal enzymes that allow them to be localized correctly in lysosomes?
lysosomal enzymes possess phosphorylated mannose residues on N-linked carbohydrate chains
What sugar is usually removed from the N-linked core oligosaccharide chains on proteins in the Golgi complex as opposed to the glucose residues trimmed off in the ER
mannose
Which type of cytoskeletal element is described as a solid structure composed of actin subunits?
microfilaments
which of the cytoskeletal elements is characterized as a hollow, rigid, cylindrical tube with was composed of tubulin subunits?
microtubules
Which enzymes hydrolyze specific ester bonds that connect the different building blocks that make up a phospholipid molecule?
phospholipases
How do protein coats select the contents of the vesicles they help form?
the coats have specific affinity for the cytosolic tails of the integral membrane
what happened to a COPI-coated vesicle within the cell that was treated with GTP analogues that could not be hydrolyzed?
they accumulated in the cytoplasm
What is the purpose for molecular chaperones like BiP and calnexin?
they bind to unfolded and misfolded proteins and help them regain their native structure
The accumulation of misfolded proteins in the ER is a potentially lethal situation and thus causes the triggering of what process?
unfolded protein response
How do Rabs appear to associate with membranes?
via a lipid anchor
