Animal DNA-Dependent RNA Polymerases. Purification and Molecular Structure of Hen-Oviduct and Liver Class-B RNA Polymerases

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Abstract
Hen oviduct and liver class B RNA polymerases (EL 2.7.7.6) were extensively purified, and their molecular structure was analyzed. While only 1 enzyme B form (BIIb) was found in liver, 3 forms (BI, BIIa and BIIb) were resolved from oviduct. The molecular structures of the various class B RNA polymerase forms purified from hen oviduct and liver are identical to the corresponding forms previously purified from calf thymus and rat liver. At the present level of resolution the only difference lies in a slight difference in the charge of one subunit (SB2a) of enzyme form BIIa, when comparing the mammal and bird enzymes. It is unlikely that the absence of enzyme forms BI and BIIa in purified hen liver RNA polymerase B could be related to limited and specific proteloysis during the purification, since co-purification of oviduct and liver RNA polymerase B activities from a mixture of oviduct and liver nuclei does not affect the presence of either oviduct enzyme form BI or BIIa in the final purified mixture.