Cross-linking of wheat germ RNA polymerase II with dithiobis(succinimidyl propionate)

The subunit arrangement of wheat germ RNA polymerase II was examined using the cleavable cross-linking reagent dithiobis(succinimidyl propionate). Conditions were chosen such that the enzyme was active prior to treatment, and that most of the subunits were reactive towards the reagent. Our results indicate that the enzyme is made up from a central core involving the two large subunits, around which the small subunits are independently arranged. Possible relations between the overall structure and the role of individual subunits in transcription are discussed.