Uridine triphosphate (UTP) is a pyrimidine nucleotide, consisting of the organic base uracil linked to the 1' carbon atom of the sugar ribose, esterified with tri-phosphoric acid at its 5'-position. Its main role is as substrate for the synthesis of RNA during transcription.
UTP also has the role of a source of energy or an activator of substrates in metabolic reactions, like that of ATP, but more specific. When UTP activates a substrate, UDP-substrate is usually formed and inorganic phosphate is released. UTP is used in the metabolism of galactose, where the activated form UDP-galactose is converted to UDP-glucose. UDP-glucose enters the synthesis of glycogen. UDP-glucuronate is used to conjugate bilirubin to a more water soluble bilirubin diglucuronide.