ABSTRACT
This chapter discusses nuclear and organellar RNA polymerases from plants and lower eukaryotes in terms of sources of enzymes, purification methodology, catalytic properties, molecular structures, immunological relationships, transcriptional functions, selectivity of transcription in nuclear and reconstituted systems, and modulation during cell cycle and growth transitions. Nuclear RNA polymerases which have been solubilized from chromatin templates by sonication in the presence of high salt or those enzymes recovered in the soluble fraction of total tissue extracts can be separated into three distinct classes by chromatography on either anionic or cationic exchange resins. Relatively large quantities of homogeneous enzyme are required for studies on RNA polymerase subunit structures, reconstitution of active enzyme from separated subunits, and in vitro transcription with reconstructed systems. The development of plant and lower eukaryotic soluble transcription systems is certainly required for future advancement in the understanding of plant and lower eukaryotic RNA polymerases and transcriptional regulation.
