The nature of the primer for glycogen synthesis in muscle.
We and others have reported that glycogenin, the covalently bound protein found in muscle glycogen, also exists in muscle in a glycogen-free form (Mr 38,000-39.000) that is autocatalytic, undergoes self-glucosylation and acts as a primer for glycogen synthesis. We now report that this entity is not present in a fresh muscle extract. Instead it exists within a pro form of much higher molecular mass which breaks down spontaneously to the Mr 38,000-39,000 form. Such breakdown is accelerated by the addition of alpha-amylase and is prevented by protease inhibitors. Multiple intermediates of the breakdown process have been detected, each capable of undergoing glucosylation.
Lomako
J
J
Department of Biochemistry and Molecular Biology, University of Miami, FL 33101.
Lomako
W M
WM
Whelan
W J
WJ
D000818:Animals; D005964:Glucosyltransferases; D006003:Glycogen / Q000096:biosynthesis* / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism*; D008970:Molecular Weight; D009132:Muscles / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D011817:Rabbits; D000516:alpha-Amylases / Q000494:pharmacology
D006023:Glycoproteins; D011498:Protein Precursors; C051887:glycogenin; D006003:Glycogen; D005964:Glucosyltransferases; D000516:alpha-Amylases