Control of juvenile hormone biosynthesis. Evidence for phosphorylation of the 3-hydroxy-3-methylglutaryl coenzyme A reductase of insect corpus allatum.

The activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase, a key enzyme of juvenile hormone biosynthesis, have been measured in the supernatants of homogenates (10,000 x g) prepared from the corpora allata of the adult tobacco hornworm moth, Manduca sexta. Enzyme activity was inhibited 80% by 50 mM NaF, a known phosphoprotein phosphatase inhibitor, if present during extirpation of the glands and all subsequent workup of the tissue. Reductase activity was also significantly decreased (20-30%) in homogenates preincubated with 4 mM MgCl2 and 2 mM ATP. These results provide evidence that reductase in the insect undergoes phosphorylation and dephosphorylation similar to that occurring with reductase of mammalian liver. If so, this would provide a rapid method for modulating juvenile hormone synthesis.