Glycogen Synthase Kinase-3 has two isoforms, GSK-3alpha and GSK3beta. GSK3 is a serine/threonine kinase that affects glycogen metabolism by phosphorylating and down-regulating the activity of muscle glycogen synthase as well as the regulation in Wnt signal pathway. GSK-3 alpha reduces the substRates beta-catenin and tau to imply an important role in Wnt signaling and tauopathies such as Alzheimers disease..