SUMMARY: Synthesis and secretion of extracellular neutral and alkaline proteases in Aspergillus nidulans are repressed in the presence of low molecular weight sources of carbon, nitrogen and sulphur; protease is formed and released when the medium is deficient for any one of these elements. Induction of protease by exogenous protein does not occur.
Activation of intracellular protease is repressed by sources of carbon, nitrogen, sulphur and phosphorus, activation taking place when any one is deficient.
These two systems of repression are independent of one another and of the two previously defined systems of ammonium repression in Aspergillus nidulans. Several classes of mutant selected for ammonium derepression also have abnormal carbon repression of protease.
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