"Superinduction" of tyrosine aminotransferase by actinomycin D: a reevaluation.

Reexamination of the effects of actinomycin D (AMD) on the intracellular level and rate of synthesis of tyrosine aminotransferase (TAT) in hepatoma tissue culture (HTC) cells reveals that much apparent controversy can be resolved with acknowledgment of the multi-faceted nature of this inhibitor's action. AMD can slow overall protein synthesis and inhibit the degradation of both TAT and its mRNA as well as block the synthesis of RNA. The extent of these secondary actions of the inhibitor depend somewhat upon the growth condition of the cells. The effects of cordycepin (3'-deoxyadenosine) on the metabolism of TAT and its mRNA are also complex, but differ in several respects from those of AMD.