Proteins that end up on the outside of the cell's plasma membrane (outer membrane) are produced by ribosomes attached to the endoplasmic reticulum (ER), and then the flow thorough the channels of the ER, where sugars get attached to their surfaces. Then they flow in the Golgi apparatus, where they are formed into vesices that travel to the cell membrane and fuse with it, becoming part of the outer membrane.
Protein X is a protein that gets to be produced y this pathway, and ends up on the outer surface of liver cells. Below is the structure of an exotic sugar that is found to be bound to tyrosine residues in thwo places on protein X. Using radioactively labeled carbons, it is detemined that all the carbons in this exotic sugar come from glucose, but the pathway is unknown.
a) Propose and write out a series of reactions (a pathway) by which this sugar could be formed, using chemical structures, and incluing all relevant substrates and co-subtrates as well as cofatos that you think are likely to beinvolved. (Try to use as few steps as possible, but hopefully no more than ten)
b) In addition, write out a reaction by which you think this exotic sugar would attach to the tyrosine residues on protein X. Show steps and structures invovled.
