The glucoamylase inhibitor acarbose is a direct activator of phosphorylase kinase.
Phosphorylase kinase (PhK), an (alphabetagammadelta)(4) complex, stimulates energy production from glycogen in the cascade activation of glycogenolysis. Its large homologous alpha and beta subunits regulate the activity of the catalytic gamma subunit and account for 81% of PhK's mass. Both subunits are thought to be multidomain structures, and recent predictions based on their sequences suggest the presence of potentially functional glucoamylase (GH15)-like domains near their amino termini. We present the first experimental evidence of such a domain in PhK by demonstrating that the glucoamylase inhibitor acarbose binds PhK, perturbs its structure, and stimulates its kinase activity.
Nadeau
Owen W
OW
Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
Liu
Weiya
W
Boulatnikov
Igor G
IG
Sage
Jessica M
JM
Peters
Jennifer L
JL
Carlson
Gerald M
GM
D020909:Acarbose / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors; D005087:Glucan 1,4-alpha-Glucosidase / Q000037:antagonists & inhibitors*; D006801:Humans; D007004:Hypoglycemic Agents; D010764:Phosphorylase Kinase / Q000737:chemistry* / Q000187:drug effects; D011485:Protein Binding; D011487:Protein Conformation
D004791:Enzyme Inhibitors; D007004:Hypoglycemic Agents; D010764:Phosphorylase Kinase; D005087:Glucan 1,4-alpha-Glucosidase; D020909:Acarbose