-!- Requires calmodulin for activity. -!- The enzyme phosphorylates a specific serine residue in each of the subunits of the dimeric phosphorylase b. -!- For muscle phosphorylase but not liver phosphorylase, this is accompanied by a further dimerization to form a tetrameric phosphorylase. -!- The enzyme couples muscle contraction with energy production via glycogenolysis--glycolysis by catalyzing the Ca(2+)-dependent phosphorylation and activation of glycogen phosphorylase b. -!- The gamma subunit of the tetrameric alpha-beta-gamma-delta enzyme is the catalytic subunit. -!- Formerly EC 2.7.1.38.