Structural comparison of deoxyribonucleic acid-dependent ribonucleic acid polymerases I and II from the slime mold Physarum polycephalum

Abstract

RNA Polymerases I and II have been purified to homogeneity from the slime mold Physarum polycephalum. When subjected to ultracentrifugation in separate sucrose gradients, or together, the two enzymes migrate with S values estimated at 14.5 S. Polyacrylamide gel electrophoresis under denaturing conditions reveals that the two enzymes have distinct but similar subunit structures. The probable subunit structure of polymerase II is as follows: 175,000 1; 140,000 1; 24,000 2; 17,000 1.