The nuclei of eukaryotic cells contain three RNA polymerases (designated I, II and III). These enzymes catalyze the formation of the phosphodiester bond that links nucleotides together to form a linear chain. Transcription by RNA polymerase III produces small, stable RNAs including tRNAs, the 5S rRNA associated with the large ribosomal subunit, one of the snRNAd required for pre-mRNA splicing, and the 7S RNA associated with the signal recognition particle involved in secretion of proteins and insertion of membrane spanning proteins into cellular membranes. The functions of many other small RNAs produced by RNA polymerase III are as yet undiscovered....