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Why is ATP an allosteric inhibitor of glycogen synthase? Wouldn't high levels of ATP in the cell mean that the cell has sufficient energy, and in this case wouldn't excess glucose be stored as glycogen? However ATP acts as an inhibitor of glycogen synthase.

What is the physiological basis/biological reason for this?

Reference:

Vasudevan D.M, Sreekumari S, Kannan Vaidyanathan 2021. Textbook of Biochemistry (For medical students) 9th ed. Pg.147

Nuttall FQ, Gannon MC. Allosteric regulation of glycogen synthase in liver. A physiological dilemma. J Biol Chem. 1993 Jun 25;268(18):13286-90. PMID: 8514767.

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    $\begingroup$ This question was asked (with similar phraseology) and answered on SE Chemistry in 2017. chemistry.stackexchange.com/questions/72741/… What’s going on here? $\endgroup$
    – David
    Jul 16, 2021 at 22:06
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    $\begingroup$ The answer there only explains the inhibition of glycogen phosporylase in detail while the question is about glycogen synthase. Moreover it explains the chemical aspect but not the physiological aspect of this inhibition. It was even suggested that the question be moved here, but no one seems to have done it. So, I posted another question. $\endgroup$ Jul 17, 2021 at 3:52
  • $\begingroup$ I doubt whether you will find a more comprehensive answer than that on SE Chemistry, where the answerer offers to respond to comments. As for physiology there is nothing about it in the original or your version of the question, or I do not understand what you mean. My own objection to the question is that it provides no documentation for or details of its premise that “ATP is an inhibitor of Glycogen Synthase”. Until I am provided with this I suspect that it is a distortion or misreading. Please edit the question to include. $\endgroup$
    – David
    Jul 17, 2021 at 8:51
  • $\begingroup$ By physiological basis, I mean the biological reason for the inhibitory effect. I have edited to include the references. $\endgroup$ Jul 17, 2021 at 13:44
  • $\begingroup$ Thanks for that. The question really boils down to the status of the 1993 paper. I was surprised to find PubMed only lists about seven citations, the latest in 1997. This suggests to me that the conclusions of the paper are not generally accepted, for whatever reason, despite being in the Indian text book you cite. Whether or not this is justified is another matter. I will revise the question accordingly when I have a moment, and do some research on it later. $\endgroup$
    – David
    Jul 17, 2021 at 17:33

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