Glutamic dehydrogenase in revertants ofammutants inneurospora

Five allelic mutants of Neurospora which lack glutamic dehydrogenase (ammutants) were induced to revert with ultra-violet. The glutamic dehydrogenase produced by the revertants was compared to that of wild-type. Several distinct classes of revertants could be distinguished by these tests. However, genetic analysis showed that all the reversions resulted from events at or near the site of the originalammutation. The spectrum of reversion types depended on the nature of theammutant employed. One mutant, which produces anamprotein believed to be altered in its active site, yielded revertants which were all indistinguishable from wild-type. Another mutant, which produces a protein with a functional active site but altered folding properties, gave at least six classes of revertants which were different from wild-type.