POLR3A : RNA polymerase III subunit A

Description

The POLR3A (RNA polymerase III subunit A) is a protein-coding gene located on chromosome 10.

The POLR3A gene provides instructions for making the largest piece (subunit) of an enzyme called RNA polymerase III. This enzyme is involved in the production (synthesis) of ribonucleic acid (RNA), a chemical cousin of DNA. The RNA polymerase III enzyme attaches (binds) to DNA and synthesizes RNA molecules in accordance with the instructions carried by the DNA, a process called transcription. RNA polymerase III helps synthesize several forms of RNA, including ribosomal RNA (rRNA) and transfer RNA (tRNA). Molecules of rRNA and tRNA assemble protein building blocks (amino acids) into working proteins; this process is essential for the normal functioning and survival of cells.

The POLR3A gene encodes a protein that is a key component of RNA polymerase III (Pol III), a complex enzyme responsible for synthesizing various small non-coding RNAs, including 5S rRNA, snRNAs, tRNAs, and miRNAs. Pol III operates through a three-stage process: initiation, elongation, and termination. During initiation, Pol III interacts with specific DNA promoters with the assistance of transcription factors. Elongation involves the synthesis of RNA using the DNA template. Finally, termination releases the RNA transcript and Pol III from the DNA. POLR3A, along with POLR3B/RPC2, forms the active center of Pol III, where each nucleotide is added to the growing RNA strand. POLR3A plays a crucial role in this process by providing a Mg(2+)-coordinating DxDGD motif, which helps in forming the phosphodiester bond between nucleotides. In addition to its role in RNA synthesis, Pol III, including POLR3A, functions as a sensor for intracellular bacteria and DNA viruses. It can detect non-self dsDNA and transcribe it into dsRNA, triggering an innate immune response. This response includes the production of type I interferon and NF-kappa-B through the RIG-I pathway. Pol III exists as two alternative complexes, each containing either POLR3G/RPC7alpha or POLR3GL/RPC7beta, which can differentially modulate Pol III's transcriptional activity.

POLR3A is also known as ADDH, C160, HLD7, RPC1, RPC155, WDRTS, hRPC155.

Associated Diseases

Comprehensive carrier screening

WES Whole Exome Sequencing

Clinical Exome Sequencing