Eukaryotic deoxyribonucleic acid-dependent ribonucleic acid polymerases: a critical assessment of current ideas concerning their multiplicity, specificity and function and their role in the regulation of gene expression.

Two comprehensive reviews of the eukaryotic DNA-dependent RNA polymerases have appeared in recent years (Chambon, 1974, 1975). It would be difficult to justify a further survey of this area within so short a period unless it was felt that this subject might benefit from a review having a rather different emphasis. We have taken a hard look at three broad areas of the subject which directly involve the RNA polymerases: (i) the definition of multiple RNA polymerases; (ii) information concerning their specificity and function, and (iii) putative direct involvement of the polymerases in the control of gene expression. Some original data are included, but for the most part a critical analysis is presented of such information as is available and the dogma which has become established in this difficult area of research.