Phosphorylase Kinase Gamma 1 (PHKg1)

PHKg1 is a member of the Ser/Thr protein kinase family and encodes a protein with one protein kinase domain and two calmodulin-binding domains. This protein is the catalytic member of a 16 subunit protein kinase complex which contains equimolar ratios of 4 subunit types. The complex is a crucial glycogenolytic regulatory enzyme. The holoenzymes are composed of 16 subunit proteins containing equimolar ratios of 4 subunit types known as alpha, beta, gamma, and delta. Skeletal muscle contains the highest amount of phosphorylase kinase enzymatic activity, although activity is also observed in liver, cardiac muscle, brain, and several other tissues. Kinetic differences exist between the cardiac and adult skeletal muscle enzymes, and the liver and skeletal muscle enzymes are known to be separate isozymes.