You are studying the process of protein glycosylation utilizing cells isolated from a breast cancer tumor. Analysis of the cells reveals that they are incapable of incorporating glucose into glycoproteins. Which of the following is most likely not synthesized, thereby preventing glycosyltransferases from incorporating glucose into the oligosaccharide portion of glycoproteins in these cells
A) AMP 1-glucose
B) CDP 6-glucose
C) glucose 1-phosphate
D) glucose 1,6-bisphosphate
E) UDP 1-glucose

Question

Quizplus · Accepted Answer

UDP-glucose is the activated form of glucose that is used by glycosyltransferases to incorporate glucose into glycoproteins. If UDP-glucose is not synthesized, glucose cannot be incorporated into glycoproteins.  The monosaccharides that are attached to proteins (as well as lipids in the formation of glycolipids) are first activated by coupling to a nucleotide. These nucleotide-activated sugars are derived from dietary sources and salvage pathways. Nucleotide-activated glucose is found as UDP-1-glucose synthesized via the activity of UDP-glucose pyrophosphorylase.

You Are Studying the Process of Protein Glycosylation Utilizing Cells