What is Rate limiting step of glycogenolysis is: and explain in detail?
Harper -145,146, 147
Glycogen phosphorylase catalyzes the rate-limiting step in glycogenolysis by promoting the phosphorolytic cleavage by inorganic phosphate of the 1-4 linkages of glycogen to yield glucose-1-phosphate. The terminal glucosyl residues from the outermost chains of the glycogen molecule are removed sequentially until approximately four glucose residues remain on either side of the 1,6 branch. Another enzyme( glucan transferase) transfers a trisaccharide unit from one branch to the other, exposing the 1,6 linkages requires the debranching enzyme. Further phosphorylase action can then proceed. The combined action of phosphorylase and these other enzymes leads to the complete breakdown of glycogen.