試題詳解

31. Which of the following descriptions about protein synthesis and targeting are correct?
(A) ER (endoplasmic reticulum) targeting of proteins synthesized in the cytosol requires a N-terminus signal sequence.
(B) Cotranslational translocation of proteins into ER lumen requires SRP (signal recognition particle) and the SRP receptor, and this protein translocation is energy-independent.
(C) a-helix of the membrane spanning domains of proteins can function as a topogenic sequence and determine the orientation of the proteins on the membrane.
(D) Most proteins in the mitochondria are encoded and synthesized in the mitochondria, and therefore do not need targeting sequences for mitochondrial localization.
(E) Proper folding of proteins require posttranslational modifications.