LOCALIZATION OF THE GENE ENCODING THE CATALYTIC GAMMA-SUBUNIT OF PHOSPHORYLASE-KINASE TO HUMAN-CHROMOSOME BANDS 7P12-Q21

Skeletal muscle phosphorylase kinase has the structure (αβγδ)4 where the α and β subunits are regulatory components, the γ subunit possesses catalytic activity and the δ subunit is identical to the calcium binding protein calmodulin. A rabbit skeletal muscle cDNA for the γ subunit has been used to map the human gene (PYKG1) to 7p12-q21, by analysis of somatic cell hybrids and in situ hybridisation. The data suggest that the skeletal muscle γ subunit gene is located just above the centromere of chromosome 7, with further cross-hybridising sequences at 7q21 and 11p11-14. The liver γ subunit is distinct and its mRNA does not cross-hybridise with the skeletal muscle γ subunit cDNA. These results indicate that autosomal human phosphorylase kinase deficiencies affecting both liver and muscle are likely to be caused by a defect in the autosomally determined β subunit, rather than the γ subunit. © 1990.