qq - ptosis

[ArchivalUser]

Which of the following best explains why proteins synthesized in the rough endoplasmic reticulum and secreted from eukaryotic cells have a shorter length than would be predicted by their respective mRNAs?
A ) Cleavage of 5r segments of nascent polypeptides being synthesized on polyribosomes in the endoplasmic reticulum
B ) Covalent binding of nascent polypeptides to specific membrane proteins during their synthesis
C ) Nonspecific protease activity during passage of these proteins through the endoplasmic reticulum membrane
D ) Shortening of the carboxy terminus because hydrophobic amino acids remain within the membrane

[ArchivalUser]

CCC? .... just guessing

[ArchivalUser]

yeah, I will go with C also

[ArchivalUser]

aaa
i think it's the N-terminal signal peptide that targets the protein to the ER, and is then removed by signal peptidase on the ER membrane

[ArchivalUser]

Others are nor, 100%.....so it's A

I am not sure what your 5r mean, please indicate.