Editing Adenosine triphosphate (section)

==Biochemical functions==
===Cellular energy production===
The conversion of ATP to ADP is the principal mechanism for energy supply in biological processes.<ref name="Myers" /> Energy is produced in cells when the terminal phosphate group in an ATP molecule is removed from the chain to produce adenosine diphosphate (ADP) when water hydrolyzes ATP:<ref name="Myers" />

ATP + H<sub>2</sub>O → ADP + HPO<sub>4</sub>{{sup|2-}} + H{{sup|+}} + energy 

However, removing a phosphate group from ADP to produce adenosine monophosphate (AMP) also produces extra energy.<ref name="Myers" />

===Intracellular signaling===
ATP is involved in [[signal transduction]] by serving as substrate for kinases, enzymes that transfer phosphate groups.  Kinases are the most common ATP-binding proteins.  They share a small number of common folds.<ref name=Scheeff>{{cite journal |last1=Scheeff |first1=E. |last2=Bourne |first2=P. | title = Structural evolution of the protein kinase-like superfamily |pmc=1261164 | doi = 10.1371/journal.pcbi.0010049 |doi-access=free | journal = PLOS Comput. Biol. | volume = 1 | issue = 5 | pages = e49 | year = 2005 | pmid = 16244704|bibcode=2005PLSCB...1...49S }}</ref>  [[Phosphorylation]] of a protein by a kinase can activate a cascade such as the [[mitogen-activated protein kinase]] cascade.<ref>{{cite journal |last1=Mishra |first1=N. |last2=Tuteja |first2=R. |last3=Tuteja |first3=N. | title = Signaling through MAP kinase networks in plants | journal = Arch. Biochem. Biophys. | volume = 452 | issue = 1 | pages = 55–68 | year = 2006 | pmid = 16806044 | doi = 10.1016/j.abb.2006.05.001 }}</ref>

ATP is also a substrate of [[adenylate cyclase]], most commonly in [[G protein–coupled receptor|G protein-coupled receptor]] signal transduction pathways and is transformed to [[second messenger]], cyclic AMP, which is involved in triggering calcium signals by the release of calcium from intracellular stores.<ref>{{cite journal |last1=Kamenetsky |first1=M. |last2=Middelhaufe |first2=S. |last3=Bank |first3=E. |last4=Levin |first4=L. |last5=Buck |first5=J. |last6=Steegborn |first6=C. | title = Molecular details of cAMP generation in mammalian cells: a tale of two systems | journal = J. Mol. Biol. | volume = 362 | issue = 4 | pages = 623–639 | year = 2006 | pmid = 16934836 | doi = 10.1016/j.jmb.2006.07.045 | pmc = 3662476}}</ref> This form of signal transduction is particularly important in brain function, although it is involved in the regulation of a multitude of other cellular processes.<ref>{{cite journal |last1=Hanoune |first1=J. |last2=Defer |first2=N. | title = Regulation and role of adenylyl cyclase isoforms | journal = Annu. Rev. Pharmacol. Toxicol. | volume = 41 | pages = 145–174 | year = 2001|issue=1 | pmid = 11264454 | doi = 10.1146/annurev.pharmtox.41.1.145 }}</ref>

===DNA and RNA synthesis===
ATP is one of four monomers required in the synthesis of [[RNA]]. The process is promoted by [[RNA polymerase]]s.<ref>{{cite journal |last1=Joyce |first1=C.&nbsp;M. |last2=Steitz |first2=T.&nbsp;A. |title=Polymerase structures and function: variations on a theme? |journal=J. Bacteriol. |volume=177 |issue=22 |pages=6321–6329 |year=1995 |pmid=7592405 |pmc=177480 |doi=10.1128/jb.177.22.6321-6329.1995}}</ref> A similar process occurs in the formation of DNA, except that ATP is first converted to the [[deoxyribonucleotide]] dATP.  Like many condensation reactions in nature, [[DNA replication]] and [[DNA transcription]] also consume ATP.

===Amino acid activation in protein synthesis===
{{main|Amino acid activation}}
[[Aminoacyl-tRNA synthetase]] enzymes consume ATP in the attachment tRNA to amino acids, forming aminoacyl-tRNA complexes. Aminoacyl transferase binds AMP-amino acid to tRNA. The coupling reaction proceeds in two steps:

# aa + ATP ⟶ aa-AMP + [[pyrophosphate|PP<sub>i</sub>]]
# aa-AMP + tRNA ⟶ aa-tRNA + AMP

The amino acid is coupled to the penultimate nucleotide at the 3′-end of the tRNA (the A in the sequence CCA) via an ester bond (roll over in illustration).

===ATP binding cassette transporter===
Transporting chemicals out of a cell against a gradient is often associated with ATP hydrolysis.  Transport is mediated by [[ATP binding cassette transporter]]s.  The human genome encodes 48 ABC transporters, that are used for exporting drugs, lipids, and other compounds.<ref>{{cite journal|title=Mammalian ABC transporters in health and disease|author1=Borst, P. |author2=Elferink, R. Oude|journal=Annual Review of Biochemistry|year=2002|volume=71|pages=537–592|doi=10.1146/annurev.biochem.71.102301.093055|pmid=12045106|s2cid=34707074 |url=https://pure.uva.nl/ws/files/3499814/42885_202387y.pdf|access-date=2018-04-20|archive-url=https://web.archive.org/web/20180421032744/https://pure.uva.nl/ws/files/3499814/42885_202387y.pdf|archive-date=2018-04-21|url-status=live}}</ref>

===Extracellular signalling and neurotransmission===
Cells secrete ATP to communicate with other cells in a process called [[purinergic signalling]]. ATP serves as a [[neurotransmitter]] in many parts of the nervous system, modulates ciliary beating, affects vascular oxygen supply etc.  ATP is either secreted directly across the cell membrane through channel proteins<ref name="RomanovLasher2018">{{cite journal|last1=Romanov|first1=Roman A.|last2=Lasher|first2=Robert S.|last3=High|first3=Brigit|last4=Savidge|first4=Logan E.|last5=Lawson|first5=Adam|last6=Rogachevskaja|first6=Olga A.|last7=Zhao|first7=Haitian|last8=Rogachevsky|first8=Vadim V.|last9=Bystrova|first9=Marina F.|last10=Churbanov|first10=Gleb D.|last11=Adameyko|first11=Igor|last12=Harkany|first12=Tibor|last13=Yang|first13=Ruibiao|last14=Kidd|first14=Grahame J.|last15=Marambaud|first15=Philippe|last16=Kinnamon|first16=John C.|last17=Kolesnikov|first17=Stanislav S.|last18=Finger|first18=Thomas E.|title=Chemical synapses without synaptic vesicles: Purinergic neurotransmission through a CALHM1 channel-mitochondrial signaling complex|journal=Science Signaling|volume=11|issue=529|year=2018|pages=eaao1815|issn=1945-0877|doi=10.1126/scisignal.aao1815|pmid=29739879|pmc=5966022}}</ref><ref name="Dahl2015">{{cite journal|last1=Dahl|first1=Gerhard|title=ATP release through pannexon channels|journal=Philosophical Transactions of the Royal Society B: Biological Sciences|volume=370|issue=1672|year=2015|pages=20140191|issn=0962-8436|doi=10.1098/rstb.2014.0191|pmid=26009770|pmc=4455760}}</ref> or is pumped into vesicles<ref name="LarssonSawada2012">{{cite journal|last1=Larsson|first1=Max|last2=Sawada|first2=Keisuke|last3=Morland|first3=Cecilie|last4=Hiasa|first4=Miki|last5=Ormel|first5=Lasse|last6=Moriyama|first6=Yoshinori|last7=Gundersen|first7=Vidar|title=Functional and Anatomical Identification of a Vesicular Transporter Mediating Neuronal ATP Release|journal=Cerebral Cortex|volume=22|issue=5|year=2012|pages=1203–1214|issn=1460-2199|doi=10.1093/cercor/bhr203|pmid=21810784|doi-access=free}}</ref> which then [[exocytosis|fuse]] with the membrane. Cells detect ATP using the [[purinergic receptor]] proteins [[P2X purinoreceptor|P2X]] and [[P2Y receptor|P2Y]].<ref>{{Cite journal |last1=Puchałowicz |first1=Kamila |last2=Tarnowski |first2=Maciej |last3=Baranowska-Bosiacka |first3=Irena |last4=Chlubek |first4=Dariusz |last5=Dziedziejko |first5=Violetta |date=2014-12-18 |title=P2X and P2Y Receptors—Role in the Pathophysiology of the Nervous System |journal=International Journal of Molecular Sciences |volume=15 |issue=12 |pages=23672–23704 |doi=10.3390/ijms151223672 |doi-access=free |issn=1422-0067 |pmc=4284787 |pmid=25530618}}</ref> ATP has been shown to be a critically important signalling molecule for [[microglia]] - [[neuron]] interactions in the adult brain,<ref>{{cite journal | url=https://www.science.org/doi/10.1126/science.aax6752 | doi=10.1126/science.aax6752   | title=Microglia monitor and protect neuronal function through specialized somatic purinergic junctions | date=2020 | last1=Csaba | first1=Cserep | last2=Balazs | first2=Pósfai | journal=Science | volume=367 | issue=6477 | pages=528–537 | pmid= 31831638 | bibcode=2020Sci...367..528C }}</ref> as well as during brain development.<ref>{{cite journal | doi=10.1016/j.celrep.2022.111369    | title=Microglial control of neuronal development via somatic purinergic junctions | date=2022 | last1=Csaba | first1=Cserep | last2=Anett | first2=Schwarcz D | journal=Cell Reports | volume=40 | issue=12 | pmid=36130488  | pmc=9513806 }}</ref> Furthermore, tissue-injury induced ATP-signalling is a major factor in rapid microglial phenotype changes.<ref>{{cite journal | doi= 10.1038/s41467-024-49773-1  | title=Microglia contribute to neuronal synchrony despite endogenous ATP-related phenotypic transformation in acute mouse brain slices | date=2024 | last1=Peter | first1=Berki | last2=Csaba | first2=Cserep | last3=Zsuzsanna | first3=Környei | journal=Nature Communications | volume= 15 | issue= 1 | page= 5402 | pmid= 38926390 | pmc=11208608 | bibcode= 2024NatCo..15.5402B }}</ref>

=== Muscle contraction ===
ATP fuels [[muscle contraction]]s.<ref>{{Cite journal |last1=Hultman |first1=E. |last2=Greenhaff |first2=P. L. |date=1991 |title=Skeletal muscle energy metabolism and fatigue during intense exercise in man |url=https://pubmed.ncbi.nlm.nih.gov/1842855/ |journal=Science Progress |volume=75 |issue=298 Pt 3-4 |pages=361–370 |issn=0036-8504 |pmid=1842855}}</ref> Muscle contractions are regulated by signaling pathways, although different [[muscle]] types being regulated by specific pathways and stimuli based on their particular function. However, in all muscle types, contraction is performed by the proteins [[actin]] and [[myosin]].<ref name=":0">{{Cite journal |last1=Kuo |first1=Ivana Y. |last2=Ehrlich |first2=Barbara E. |date=February 2015 |title=Signaling in Muscle Contraction |journal=Cold Spring Harbor Perspectives in Biology |language=en |volume=7 |issue=2 |pages=a006023 |doi=10.1101/cshperspect.a006023 |issn=1943-0264 |pmc=4315934 |pmid=25646377}}</ref>

ATP is initially bound to myosin. When [[ATPase]] hydrolyzes the bound ATP into [[Adenosine diphosphate|ADP]] and inorganic [[phosphate]], myosin is positioned in a way that it can bind to actin. Myosin bound by ADP and P<sub>i</sub> forms cross-bridges with actin and the subsequent release of ADP and P<sub>i</sub> releases energy as the power stroke. The power stroke causes actin filament to slide past the myosin filament, shortening the muscle and causing a contraction. Another ATP molecule can then bind to myosin, releasing it from actin and allowing this process to repeat.<ref name=":0" /><ref>{{Cite web |date=2018-07-16 |title=38.17: Muscle Contraction and Locomotion - ATP and Muscle Contraction |url=https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book%3A_General_Biology_(Boundless)/38%3A_The_Musculoskeletal_System/38.17%3A_Muscle_Contraction_and_Locomotion_-_ATP_and_Muscle_Contraction |access-date=2024-05-01 |website=Biology LibreTexts |language=en}}</ref>

=== Protein solubility ===
ATP has recently been proposed to act as a biological [[hydrotrope]]<ref>{{Cite journal|last1=Hyman|first1=Anthony A.|last2=Krishnan|first2=Yamuna|last3=Alberti|first3=Simon|last4=Wang|first4=Jie|last5=Saha|first5=Shambaditya|last6=Malinovska|first6=Liliana|last7=Patel|first7=Avinash|date=2017-05-19|title=ATP as a biological hydrotrope|journal=Science|language=en|volume=356|issue=6339|pages=753–756|doi=10.1126/science.aaf6846|issn=0036-8075|pmid=28522535|bibcode=2017Sci...356..753P|s2cid=24622983}}</ref> and has been shown to affect proteome-wide solubility.<ref>{{Cite journal|last1=Savitski|first1=Mikhail M.|last2=Bantscheff|first2=Marcus|last3=Huber|first3=Wolfgang|last4=Dominic Helm|last5=Günthner|first5=Ina|last6=Werner|first6=Thilo|last7=Kurzawa|first7=Nils|last8=Sridharan|first8=Sindhuja|date=2019-03-11|title=Proteome-wide solubility and thermal stability profiling reveals distinct regulatory roles for ATP|journal=Nature Communications|language=en|volume=10|issue=1|pages=1155|doi=10.1038/s41467-019-09107-y|pmid=30858367|pmc=6411743|bibcode=2019NatCo..10.1155S|issn=2041-1723}}</ref>