Regulation of glycogen phosphorylase in fat body ofCecropia silkmoth pupae

Abstract

Glycogen phosphorylase of pupal fat body of the silkmoth,Hyalophora cecropia, and its activation by different stimuli have been studied. Spectrophotometric assay in the direction of glycogenolysis, used in most of the experiments, indicated higher amounts of phosphorylasea than assay by release of Pi from glucose-1-phosphate; both assays, however, estimated changes in proportion of phosphorylasea equally. TheKms for Pi were estimated as 5 mM for phosphorylasea in the absence of AMP and 18 mM for phosphorylaseb with 2 mM AMP.