Regulation of Sulfate Assimilation in Plants: 7. Cysteine Inactivation of Adenosine 5'-Phosphosulfate Sulfotransferase in Lemna minor L

When 0.5 mm cysteine is added to cultures of Lemna minor L. growing with sulfate as the sole sulfur source, there is a rapid 80% loss of extractable adenosine 5′-phosphosulfate sulfotransferase. This loss is accompanied by an inhibition of sulfate uptake; however, lack of sulfate is not responsible for the decreasing adenosine 5′-phosphosulfate sulfotransferase activity.