11 Protein Sorting
Which of the following is NOT a mechanism that localizes proteins within intracellular compartments?
A) Vesicle transport
B) Transmembrane deletion
C) Transmembrane insertion
D) Gated entry
E) None of the above
What criteria is required for nuclear transportation of large molecules?
A) Large molecules require a nuclear localization signal, a receptor, and molecular chaperones.
B) Large molecules require a receptor, ATP, and molecular chaperones.
C) Large molecules require a nuclear localization signal and a receptor.
D) Large molecules require a nuclear localization signal, a receptor, and GTP.
Which of the following statements are true regarding the importation of proteins into the mitochondria? (select all that apply)
A) The signaling sequence on the precursor protein is recognized by TOM/TIM complex.
B) Importation occurs during translation/synthesis of the protein.
C) Signal sequence is found on C-terminal end of precursor protein.
D) Signaling sequence is cleaved after the protein enters the mitochondrion.
Which of the following events could happen to a protein in the secretory pathway?
A) It’s signal sequence could be cleaved
B) It could acquire carbohydrate residues
C) It could be proteolytically processed
D) It could acquire intra-chain disulfide bonds
E) All of the above
Sugars are modified in which two organelles?
A) ER and mitochondria
B) Mitochondria and golgi
C) ER and golgi
D) ER and lysosomes
E) None of the above
In what form do proteins cross the mitochondrial membranes?
A) Bound to an importin protein via a signal sequence
B) In fully folded form
C) In unfolded, extended form attached to Hsp 70 chaperones
D) In unfolded, extended form without chaperones
What constitutes the driving force for transport of proteins into and out of the nucleus?
A) ATP hydrolysis within the cytosol
B) ATP hydrolysis within the nucleus
C) GTP hydrolysis within the cytosol
D) GTP hydrolysis within the nucleus
Where do proteins, inserted into the inner mitochondrial membrane, originate?
A) In the cytosol, inserted using the outer and inner membrane translocases (TOMs and TIMs) and in the matrix, inserted using TIMs.
B) In the cytosol, inserted using outer membranes translocases (TOMs) and inner membrane translocases (TIMs).
C) In the matrix, inserted using inner membrane translocases (TIMs).
D) None of the above
Which of the following is transported out of the nucleus across the nuclear pore?
B) Ribosomal RNA
C) Ribosomal proteins
Which of the following interacts with signal recognition particle (SRP) during protein synthesis?
A) Nuclear matrix protein
B) Lysosomal hydrolase
C) Peroxisomal protein
D) Mitochondrial protein (or its precursor)
E) Chloroplast protein