Phosphorylation of sites 3 and 2 in rabbit skeletal muscle glycogen synthase by a multifunctional protein kinase (ATP-citrate lyase kinase).

摘要: A multifunctional protein kinase, purified from rat liver as ATP-citrate lyase has been identified a glycogen synthase kinase. This kinase catalyzed incorporation of up to 1.5 mol 32PO4/mol subunit associated with decrease in the activity ratio 0.85 value 0.15. Approximately 65-70% 32PO4 was incorporated into site 3 and 30-35% 2 determined by reverse phase high performance liquid chromatography. Release phosphopeptides during automated Edman degradation confirmed assignment. Thermal stability studies established that phosphorylations sites were same distinguished kinase-3 on basis nucleotide (ATP versus GTP) substrate (glycogen synthase, lyase, acetyl-CoA carboxylase) specificities. Since phosphate contents are altered diabetes insulin administration, possible involvement explored. Glycogen diabetic rabbits phosphorylated vitro this at only 10% rate compared control rabbits. Treatment diabetics restored form readily vitro.