Question

Indicate whether the C-terminus (C) or the N-terminus (N) of each of the following proteins is expected to be located in the cytosol upon membrane integration of the protein. Your answer would be a three-letter string composed of letters C and N only, e.g. CCC.
(A) A single-pass transmembrane protein that has one N-terminal signal sequence and one internal stop-transfer signal
(B) A single-pass transmembrane protein that has one internal signal sequence that is preceded by a patch of positively charged residues
(C) An ER tail-anchored protein

Answer 1

Answer:

The correct answer is - CNN.

Explanation:  

Protein modification or folding takes place in the endoplasmic reticulum. The Endoplasmic Reticulum modifies the amino acids according to their signal sequences and tail. The following case can help in indicating the C-terminus (C) or the N-terminus (N) of each of the following proteins-

A) the C-terminus would be placed in the cytosol and the N-terminus in the endoplasmic reticulum lumen after cleaving the N-terminal signal sequence.

B) The N -terminal is the positive end of the chain and as per the rule of positive inside it allows N terminal in the cytosol

( C ) Tail-anchored proteins always have their N-terminal bulk in the cytosol.

Thus, CNN would be the correct answer from the explanation given above.