The oligosaccharide block that is added to secretory proteins after they enter the ER lumen goes through a number of modifications after its attachment. What is the first modification that occurs?
A)addition of more sugars
B)addition of glucose
C)trimming of some sugars from the oligosaccharide block
D)chemical modification of the sugars on the oligosaccharide chain
E)both addition of more sugars and addition of glucose

Question

Quizplus · Accepted Answer

The first modification that occurs to the oligosaccharide block is trimming of some sugars from the block. This is done by enzymes in the ER and is important for proper folding of the protein.

The Oligosaccharide Block That Is Added to Secretory Proteins After