5 A) Which of the following statements about apical and basolateral protein sort
ID: 219878 • Letter: 5
Question
5 A) Which of the following statements about apical and basolateral protein sorting is FALSE?
Transcytosis is a mechanism for the movement of basolaterally secreted proteins to the apical membrane.
Infection of epithelial cells with specific viral proteins has helped elucidate the mechanisms of polarized protein secretion.
GPI-linked proteins are sorted specifically to the apical membrane of most polarized epithelial cells.
Vesicles that bud from the trans-Golgi network travel specifically to the apical membrane.
5 B) How does lysosomal pH contribute to lysosomal protein sorting?
Lysosomal proteins only properly fold at the acidic pH found in the lysosome.
Acidic pH is required for fusion of clathrin-coated vesicles with the lysosomal membrane.
Clathrin/AP1 vesicles that travel to the lysosome have a high affinity for lysosomal membranes due to their low pH.
The mannose-6-phosphate receptor has altered affinity for M6P under acidic pH conditions.
Explanation / Answer
5 (A).
Correct: the false statement is that, infection of epithelial cells with specific viral proteins has helped elucidate the mechanism of polarized protein secretion. This because every infection does not lead to the secretion of polarized protein.
Hence, the correct option is (2).
Incorrect: all the other statements are true for the protein sorting.
Hence, the options (1), (3) and (4) are incorrect.
5 (B).
Correct: lysosomal proteins play an important role as they act as enzymes and also perform several other functions. The proper folding of these proteins is maintained by the acidic pH found in the lumen of lysosome.
Hence, the correct option is (1).
Incorrect: all the other working given in other options occur under the pH f nearly 6.7. Alsi there functioning do not affected by the little change in the pH.
Hence, the options (2), (3) and (4) are incorrect.
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