Skeletal muscle glycogen a4-synthase (EC 2.4.1.11) has been purified free of all synthase kinase and phosphatase activities by chromatography on a Glc-N-6-P-Sepharose affinity column and then on a phosphocellulose column. This preparation of glycogen synthase was tested as a substrate for purified skeletal muscle phosphorylase kinase (ATP:phosphorylase-b phosphotransferase, EC 2.7.1.38). Phosph...

We have studied the control of insulin-regulated protein kinases in Chinese hamster ovary cells transfected with the human insulin receptor (CHO.T cells). Among these enzymes is one that is obtained after chromatography of cell extracts on Mono-S, whose activity is decreased (7.3 +/- 1.9-fold) within 10 min of insulin treatment. This enzyme phosphorylates glycogen synthase and the largest subun...

A rapid method for purifying glycogen synthase a from rat liver was developed and the enzyme was tested as a substrate for nine different protein kinases, six of which were isolated from rat liver. The enzyme was phosphorylated on a 17-kDa CNBr fragment to approximately 1 phosphate/87-kDa subunit by phosphorylase b kinase from muscle or liver with a decrease in the activity ratio (-Glc-6-P/+Glc...

Cardiac dysfunction is a severe secondary effect of Type 2 diabetes. Recruitment of the protein kinase B/glycogen synthase kinase-3 pathway represents an integral event in glucose homeostasis, albeit its regulation in the diabetic heart remains undefined. Thus the following study tested the hypothesis that the regulation of protein kinase B/glycogen synthase kinase-3 was altered in the myocardi...

Studies of skeletal muscle from rodents performed both in vivo and in vitro suggest a regulatory role of glycogen synthase kinase (GSK) 3 in glycogen synthase (GS) activation in response to insulin. Recently, hyperinsulinemic clamp studies in humans support such a role under nearly physiological conditions. In addition, in rats the activation of GS in skeletal muscle during treadmill running is...

The effects of hypothyroidism on glycogen metabolism in rat skeletal muscle were studied using the perfused rat hindlimb preparation. Three weeks after propylthiouracil treatment, serum thyroxine was undetectable and muscle glycogen and Glc-6-P were decreased. Basal and epinephrine-stimulated phosphorylase a and phosphorylase b kinase activities were also significantly reduced, as were epinephr...

Genes in the Wnt (wingless)/ β -catenin signaling pathway have been implicated in schizophrenia pathogenesis. No study has examined this pathway in the broader context of psychosis symptom severity. We investigated the association between symptom severity scores and expression of 25 Wnt pathway genes in blood from 19 psychotic patients. Significant correlations between negative symptom scores a...