RNA Polymerase III

High Quality Content by WIKIPEDIA articles! RNA polymerase III (also called Pol III) transcribes DNA to synthesize ribosomal 5S rRNA, tRNA and other small RNAs. The genes transcribed by RNA Pol III fall in the category of "housekeeping" genes whose expression is required in all cell types and most environmental conditions. Therefore the regulation of Pol III transcription is primarily tied to the regulation cell growth and the cell cycle, thus requiring fewer regulatory proteins than RNA polymerase II. Initiation: the construction of the polymerase complex on the promoter. Pol III is unusual (compared to Pol II) requiring no control sequences upstream of the gene, instead normally relying on internal control sequences - sequences within the transcribed section of the gene (although upstream sequences are occasionally seen, eg. U6 snRNA gene has an upstream TATA box as seen in Pol II Promoters).