RNA polymerase III (Pol III) is a multi-subunit complex responsible for catalyzing
the transcription of DNA into RNA. POLR3A (polymerase (RNA) III (DNA
directed) polypeptide A), also known as RPC1 or RPC155, is a 1,390 amino acid
protein that localizes to the nucleus and belongs to the RNA polymerase β
chain family. Existing as the largest and catalytic core component of Pol III,
POLR3A functions as a DNA-dependent RNA polymerase that catalyzes the
conversion of a nucleoside triphosphate into a diphosphate, thereby transcribing
DNA into RNA. The gene encoding POLR3A maps to human chromosome
10, which houses over 1,200 genes and comprises nearly 4.5% of the human
genome. Defects in some of the genes that map to chromosome 10 are associated
with Charcot-Marie Tooth disease, Jackson-Weiss syndrome, Usher
syndrome, nonsyndromatic deafness, Wolman’s syndrome, Cowden syndrome,
multiple endocrine neoplasia type 2 and porphyria.