Eukaryotes produce 3 distinct classes of RNA polymerase, Pol I, II and III. Each polymerase is responsible for the synthesis of a different class of RNA. RNA polymerase III (Pol III) transcribes the 5S rRNA genes and all of the tRNA (transfer RNA) genes. POLR3K, also known as DNA-directed RNA polymerase III subunit RPC11, is a 108 amino acid nuclear protein that is one of the seventeen subunits that comprise Pol III. Specifically, POLR3K is a DNA-dependent RNA polymerase that uses the four ribonucleoside triphosphates to catalyze the transcription of DNA to RNA. The gene encoding POLR3K maps to human chromosome 16, which encodes over 900 genes in approximately 90 million base pairs and is associated with a variety of genetic disorders.
