The effect of the carbon source on ammonium regulation in Aspergillus nidulans

Summary Ammonium regulation of L-glutamate transport is annuled when L-glutamate is the sole or main carbon source. This shows that ammonium regulation mechanisms are not operative where the substrate of the ammonium repressible system can be used as a carbon as well as a nitrogen source. There is rapid loss of NADP L-glutamate dehydrogenase when glucose is replaced by L-glutamate as a carbon source. This suggests that NADP L-glutamate dehydrogenase may be subject to carbon as well as nitrogen control.