DNA Directed RNA Polymerase, Mitochondrial (POLRMT)

Mitochondria of all organisms contain a genome that is distinct from that of the nucleus. The circular mitochondrial chromosome contains 37 genes that encode the RNA components of the mitochondrial translational apparatus, i.e., 22 transfer RNAs and 2 ribosomal RNA genes, as well as 13 polypeptide-encoding genes.

POLRMT encodes a mitochondrial DNA-directed RNA polymerase. The gene product is responsible for mitochondrial gene expression as well as for providing RNA primers for initiation of replication of the mitochondrial genome. Although this polypeptide has the same function as the three nuclear DNA-directed RNA polymerases, it is more closely related to RNA polymerases of phage and mitochondrial polymerases of lower eukaryotes.