Uridine-5′-triphosphate (UTP) is a
pyrimidine
Pyrimidine (; ) is an aromatic, heterocyclic, organic compound similar to pyridine (). One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has nitrogen atoms at positions 1 and 3 in the ring. The oth ...
nucleoside triphosphate
A nucleoside triphosphate is a nucleoside containing a nitrogenous base bound to a 5-carbon sugar (either ribose or deoxyribose), with three phosphate groups bound to the sugar. They are the molecular precursors of both DNA and RNA, which are chai ...
, consisting of the
organic base uracil
Uracil () (nucleoside#List of nucleosides and corresponding nucleobases, symbol U or Ura) is one of the four nucleotide bases in the nucleic acid RNA. The others are adenine (A), cytosine (C), and guanine (G). In RNA, uracil binds to adenine via ...
linked to the 1′ carbon of the
ribose
Ribose is a simple sugar and carbohydrate with molecular formula C5H10O5 and the linear-form composition H−(C=O)−(CHOH)4−H. The naturally occurring form, , is a component of the ribonucleotides from which RNA is built, and so this comp ...
sugar, and esterified with tri-
phosphoric acid
Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, ...
at the 5′ position. Its main role is as substrate for the synthesis of
RNA
Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...
during
transcription. UTP is the precursor for the production of
CTP via
CTP synthetase. UTP can be biosynthesized from UDP by Nucleoside Diphosphate Kinase after using the phosphate group from ATP. UDP + ATP ⇌ UTP + ADP;
both UTP and ATP are energetically equal.
The homologue in DNA is
thymidine triphosphate (TTP or dTTP). UTP also has a deoxyribose form (dUTP).
Role in metabolism
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 (such as glucose-1-phosphate), UDP-glucose is formed and inorganic phosphate is released.
UDP-glucose enters the synthesis of
glycogen
Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. It is the main storage form of glucose in the human body.
Glycogen functions as one of three regularly used forms ...
. UTP is used in the metabolism of
galactose
Galactose (, ''wikt:galacto-, galacto-'' + ''wikt:-ose#Suffix 2, -ose'', ), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweetness, sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epime ...
, where the activated form
UDP-galactose is converted to UDP-glucose.
UDP-glucuronate is used to conjugate
bilirubin
Bilirubin (BR) (adopted from German, originally bili—bile—plus ruber—red—from Latin) is a red-orange compound that occurs in the normcomponent of the straw-yellow color in urine. Another breakdown product, stercobilin, causes the brown ...
to a more water-soluble
bilirubin diglucuronide. UTP is also used to activate amino sugars like glucosamine-1-phosphate to UDP-glucosamine, and ''N''-acetyl-glucosamine-1-phosphate to UDP-''N''-acetylglucosamine.
Role in receptor mediation
UTP also has roles in mediating responses by extracellular binding to the P2Y receptors of cells. UTP and its derivatives are still being investigated for their applications in human medicine. However, there is evidence from various model systems to suggest it has applications in pathogen defense and injury repair. In mice UTP has been found to interact with P2Y4 receptors to mediate an enhancement in antibody production. In Schwannoma cells, UTP binds to the P2YP receptors in the event of damage. This leads to the downstream signal cascade that leads to the eventual injury repair.
See also
*
CTP synthase
References
{{DEFAULTSORT:Uridine Triphosphate
Nucleotides
Gene expression
Metabolism
Phosphate esters
Pyrimidinediones