DNA-dependent RNA polymerase activities in hepatopancreas nuclei from Mytilus galloprovincialis Lamarck.

ABSTRACT

It has been shown that RNA synthesis in isolated hepatopancreas nuclei from Mytilus galloprovincialis is catalyzed by three DNA-dependent RNA polymerases (I, II and III) which resemble those identified in nuclei from mammalian cells. RNA polymerase I is active at 50 mM (NH4)2SO4, catalyzes the synthesis of GMP-rich ribosomal-like RNA and is completely resistant to the toadstool toxin alpha-amanitin. RNA polymerase II and III are active at higher (NH4)2SO4 concentrations, catalyze the synthesis of DNA-like RNA and are inhibited by very low (0.5-1 microgram/ml) and high (200 microgram/ml) concentrations of alpha-amanitin, respectively. Hepatopancreas nuclei retain considerable RNAase activity. Nuclear RNA polymerase activity may be underestimated since a part of the synthetized RNA is degraded.