Purification and Characterization of Soybean DNA-Dependent RNA Polymerases and the Modulation of Their Activities During Development

Abstract

Following the report of Roeder and Rutter, (1, 2) describing multiple forms of RNA polymerase in animal cells, studies on the structure and function of the eukaryotic RNA polymerases have progressed rapidly. Three major classes of nuclear RNA polymerase have been described: I or A, II or B, and III or C (1–5). The nomenclature used throughout this paper is that adopted from Roeder and Rutter (1) which is derived from the elution pattern of the RNA polymerases from DEAE Sephadex. Each class has distinguishing characteristics (i.e., sensitivity to the fungal toxin, a-amanitin, elution patterns from cation and anion exchange resins, salt optima, and template preferences) as well as distinct subunit structures (5–9). In addition, each of the three classes can be subdivided into 2 or 3 species which are resolved by gel electrophoresis under both denaturing and nondenaturing conditions (7–9).