Phosphorylase b kinase gamma catalytic chain, liver/testis isoform is a protein in humans that is encoded by PHKG2 gene. Catalytic subunit of the phosphorylase b kinase (PHK), which mediates the neural and hormonal regulation of glycogen breakdown (glycogenolysis) by phosphorylating and thereby activating glycogen phosphorylase. May regulate glycogeneolysis in the testis. In vitro, phosphorylates PYGM (By similarity).