POLR3B : RNA polymerase III subunit B
Description
The POLR3B (RNA polymerase III subunit B) is a protein-coding gene located on chromosome 12.
The POLR3B gene provides instructions for making one part (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 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 POLR3B gene provides instructions for making a subunit of RNA polymerase III (Pol III), a DNA-dependent enzyme responsible for synthesizing small non-coding RNAs like 5S rRNA, snRNAs, tRNAs, and miRNAs from various genomic loci. Pol III's transcription cycle involves initiation, elongation, and termination phases. During initiation, Pol III binds to DNA promoters with the help of specific factors. The polymerase then transcribes RNA based on the DNA sequence during elongation, followed by termination, where the RNA transcript and polymerase detach from DNA. POLR3B/RPC2 collaborates with POLR3A/RPC1 to form Pol III's active center, where it aids in coordinating a magnesium ion and provides lysine residues for nucleotide base pairing. This process involves appending nucleotides to the growing RNA chain, with POLR3A/RPC1 and POLR3B/RPC2 playing crucial roles in coordinating magnesium ions and facilitating base pairing. Beyond transcription, Pol III plays a vital role in sensing and limiting infections by bacteria and viruses. Acting as a nuclear and cytosolic DNA sensor, it detects non-self dsDNA, which serves as a template for dsRNA transcription. These non-self RNA polymerase III transcripts, such as Epstein-Barr virus-encoded RNAs (EBERs), trigger the immune response via the RIG-I pathway, leading to the production of type I interferon and NF-kappa-B.
POLR3B is also known as C128, CMT1I, HLD8, INMAP, RPC2.
Associated Diseases
- Charcot-Marie-Tooth disease, demyelinating, type 1I
- Hypomyelination-hypogonadotropic hypogonadism-hypodontia syndrome
- Leukodystrophy, hypomyelinating, 7, with or without oligodontia and/orhypogonadotropic hypogonadism
- Leukodystrophy, hypomyelinating, 8, with or without oligodontia and/or hypogonadotropic hypogonadism
- Pol III-related leukodystrophy
