RNA polymerases transcribe nuclear genes for ribosomal RNA, thus representing ribosomal biogenesis. RNA polymerase I (Pol I) is located in the nucleolus and transcribes class I genes, which code for large ribosomal RNA. Different subunits of the Pol I transcription machinery are targets of various physiological stimuli, which suggests that multiple signaling pathways are involved in carrying out Pol I transcription. RPA40 and RPA16 are subunits of Pol I that associate with each other at an early stage of RNA polymerase I assembly. RPA40 is essential for the function and integrity of the complex and is also an essential subunit of RNA polymerase III (Pol III). RPA40, RPA16 and RPA135 encode the three subunits of RNA polymerase I, respectively. RPA194 is the largest subunit of RNA Pol I and is not a component of Pol II and Pol III.
A190; DNA-directed RNA polymerase I largest subunit; DNA-directed RNA polymerase I subunit A; DNA-directed RNA polymerase I subunit A1; DNA-directed RNA polymerase I subunit RPA1; POLR1A; polymerase (RNA) I polypeptide A, 194kDa; polymerase (RNA) I subunit A; RNA polymerase I 194 kDa subunit; RNA polymerase I subunit A1; RPA194