BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Glycogenin is an enzyme involved in converting glucose to glycogen. It acts as a primer, by polymerizing the first few glucose molecules, after which other enzymes take over. It is a homodimer of 37-kDa subunits and is classified as a glycosyltransferase.

Detailed explanation-2: -Glycogenin (GYG1 or GYG2) (EC 2.4. 1.1. 86) functions as the primer for glycogen synthesis and is a self-glycosylating enzyme that uses uridine diphosphoglucose to synthesize a short glucose polymer attached to a surface tyrosine residue.

Detailed explanation-3: -Glycogenin undergoes self-glucosylation to generate an oligosaccharide primer, which, when long enough, supports the action of glycogen synthase to elongate the polysaccharide chain, leading ultimately to the formation of glycogen. We report that primed glycogenin is also a substrate for glycogen phosphorylase.

Detailed explanation-4: -Glycogen synthase (UDP-glucose-glycogen glucosyltransferase) is a key enzyme in glycogenesis, the conversion of glucose into glycogen. It is a glycosyltransferase (EC 2.4.

Detailed explanation-5: -Pitcher et al. (7) proposed that glycogenin is a “subunit” of glycogen synthase. In liver, however, the ratio of glycogenin to glycogen synthase is much lower, making a stoichiometric association similar to that seen in muscle improbable (19). Yeast Glg proteins are also likely to interact with glycogen synthase (17).