myophosphorylase

enzyme

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 22, 2026

Quick Summary

Myophosphorylase is an enzyme crucial for glycogenolysis, the process of breaking down stored glycogen into glucose for energy. This enzyme catalyzes the initial step in this breakdown, splitting off glucose-1-phosphate units from glycogen.12

A deficiency in myophosphorylase leads to McArdle disease (glycogen storage disease type V), a muscle disorder. Individuals with this condition experience muscle cramps during exercise because their muscles cannot adequately break down glycogen for energy. This highlights the enzyme's vital role in muscle function and energy metabolism.123

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

3 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

McArdle disease
…which encodes an enzyme called myophosphorylase that specializes in the breakdown of glycogen specifically in muscle cells. Mutations in PYGM may be inherited from one or both parents, with full-blown disease arising from autosomal recessive inheritance (both parents passing mutations to offspring). When mutated, PYGM encodes a less functional form…
Read More
…which encodes an enzyme called myophosphorylase that specializes in the breakdown of glycogen specifically in muscle cells. Mutations in PYGM may be inherited from one or both parents, with full-blown disease arising from autosomal recessive inheritance (both parents passing mutations to offspring). When mutated, PYGM encodes a less functional form…
Read More