Phosphorylase kinase complex (activates glycogenolysis) — GSD IX

The phosphorylase kinase (alpha-beta-gamma-delta)4 holoenzyme grounded to the human subunits PHKG2 (catalytic gamma, UniProtKB:P15735, GO:0004689, EC 2.7.11.19), the regulatory alpha subunits PHKA1 (P46020, muscle) / PHKA2 (P46019, liver) and the regulatory beta subunit PHKB (Q93100). GO molecular-function terms were taken from the human GOA records; the catalytic annoton uses the phosphorylase kinase activity term, while the non-catalytic alpha/beta annotons use calmodulin binding (their experimentally-supported MF) with the regulatory role described in text — the complex's catalytic activity resides solely in the gamma subunit. Reactome reaction ids and titles were verified against the local reactome cache. The gamma subunit uses PANTHER PTHR24347 (a broad Ser/Thr-kinase family; the phosphorylase-kinase catalytic subfamily), and the alpha and beta subunits share PANTHER PTHR10749 (phosphorylase b kinase regulatory subunit) — PHKA1/PHKA2 as alpha representatives and PHKB as the beta representative. The delta subunit is calmodulin (CALM1/CALM2/ CALM3), a distinct tightly-bound protein that confers Ca2+ sensitivity and is not reviewed here. Functionally, activated PhK phosphorylates glycogen phosphorylase b -> a (human Reactome R-HSA-71588 liver / R-HSA-71541 muscle), the activation input to the phosphorylase step of the glycogenolysis module (positive regulation of glycogen catabolic process, GO:0045819). Disorders: PHKA2 -> GSD IXa (X-linked liver); PHKB -> GSD IXb; PHKG2 -> GSD IXc; PHKA1 -> GSD IXd (X-linked muscle).