The statement "Glycogen synthase is regulated via negative feedback by AMP, epinephrine, and glucagon" is misleading for the following reasons:
Incorrect use of "negative feedback":
Negative feedback implies that a product of a pathway inhibits its own synthesis to maintain homeostasis.
AMP, epinephrine, and glucagon are not products of glycogen synthesis; thus, their action does not constitute negative feedback.
Mechanism of regulation:
AMP inhibits glycogen synthase allosterically, primarily in skeletal muscle, as part of an energy-sensing mechanism.
Epinephrine and glucagon inhibit glycogen synthase via hormonal signaling (cAMP → PKA → phosphorylation), which is feedforward, not feedback.
Correct phrasing:
A more accurate statement would be:
"Glycogen synthase is inhibited by AMP, epinephrine, and glucagon."
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