Suppression of the accumulation of steroid-inducible glutamine synthetase mRNA on embryonic chick retinal polysomes by interferon preparation.

The suppression mechanism of glutamine synthetase [EC 6.3.1.2] induction mediated by chick interferon preparation was investigated in embryonic chick neural retina cell cultures. A translational assay was used to measure the level of mRNA coding for the enzyme. RNA extracted from the retinal polysomes was chromatographed on oligo(dT)-cellulose and translated in a cell-free protein synthesizing system derived from wheat germ. The newly synthesized enzyme was isolated by immunoprecipitation with anti-enzyme gamma-globulin and identified using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Neither polysomal profiles nor total protein synthesis directed by the RNA preparations was affected by interferon treatment. Comparing the amount of glutamine synthetase synthesized in vitro by equal amounts of mRNA fraction from retinas treated with or without interferon indicated that the suppression was associated with reduced level of the enzyme mRNA on polysomes.