What stops glycogenolysis?

[busyNDstudent]

The obvious answer is that there is no glycogen left, but I recall that it proceeds more slowly with time during a fast. A table in the notes shows consumption declining over time. I recall that there is some kind of control that governs this slowing of glycogen degradation, but I can't remember the name of the process, feedback, or enzyme that is responsible. I have tried Marks' Basic Medical Biochemistry, Silverthorn Human Physiology , the class notes, and Google. They were all a no go. the way the question is worded I am looking for something that acts on phosphatase 1 and phosphorylase.

 

 

[Elite Engineer]

I am looking for something that acts on phosphatase 1 and phosphorylase.

 

 

You mean an enzyme inhibitor?

Just a 3 second google search. Not sure if it's what you're looking for...

 

https://www.ncbi.nlm.nih.gov/pubmed/9374671

 

from the article: "...administration of BAY R 3401, a glycogen phosphorylase inhibitor."

Edited November 27, 2016 by Elite Engineer

[CharonY]

The obvious answer is that there is no glycogen left, but I recall that it proceeds more slowly with time during a fast. A table in the notes shows consumption declining over time. I recall that there is some kind of control that governs this slowing of glycogen degradation, but I can't remember the name of the process, feedback, or enzyme that is responsible. I have tried Marks' Basic Medical Biochemistry, Silverthorn Human Physiology , the class notes, and Google. They were all a no go. the way the question is worded I am looking for something that acts on phosphatase 1 and phosphorylase.

 

 

 

Depends on context. Physiologically, the regulation is mediated by a feedback loop that is based on blood sugar levels and involves glucagon and insulin as the key (antagonistic) players. At least, that would be a decent starting point.

Edited November 27, 2016 by CharonY

[BabcockHall]

This is a very complex question. One might consult Nelson and Cox, Principles of Biochemistry, Chapter 15 for some reading. The regulation of phosphoprotein phosphatase-1 is a key control point, as you imply. There is an inhibitor of this protein (inhibitor 1) that can be reversibly phosphorylated. Second, the regulation of glycogen-targeting protein GM is worth examining. It can be phosphorylated in two different locations, by different hormones (insulin versus epinephrine). Finally some isoforms of cyclic AMP phosphodiesterase are regulated, but to the best of my knowledge, not all are. IIRC regulation of an isozyme of cAMP phosphodiesterase might be more important in certain kinds of lipid metabolism, but I could be wrong.

[BabcockHall]

The obvious answer is that there is no glycogen left, but I recall that it proceeds more slowly with time during a fast.

 

 

An abundance of blood glucose would be expected to stop glycogenolysis in the liver. Therefore, one should look at how insulin regulates the key enzymes.