Editing Cyclic nucleotide (section)

===Synthesis and Degradation===
[[File:Cyclic nucleotide synthesis.png|thumb|Generic cyclic nucleotide biosynthesis reaction by cyclase]]
Cyclic nucleotides are produced from the generic reaction NTP → cNMP + PP<sub>i</sub>,<ref name="camp">{{cite web |url=https://www.nlm.nih.gov/cgi/mesh/2011/MB_cgi?mode=&term=Adenylate+cyclase |title=National Library of Medicine - Medical Subject Headings, Adenylyl Cyclase }}</ref> where N represents a nitrogenous base.  The reaction is catalyzed by specific nucleotidyl cyclases, such that production of cAMP is catalyzed by [[adenylyl cyclase]] and production of cGMP is catalyzed by [[guanylyl cyclase]].<ref name="newton">{{cite journal |vauthors=Newton RP, Smith CJ |title=Cyclic nucleotides |journal=Phytochemistry |volume=65 |issue=17 |pages=2423–37 |date=September 2004 |pmid=15381406 |doi=10.1016/j.phytochem.2004.07.026 }}</ref>  [[Adenylyl cyclase]] has been found in both a transmembrane and [[cytosol]]ic form, representing distinct protein classes and different sources of cAMP.<ref name="Flacke">{{cite journal |vauthors=Flacke JP, Flacke H, Appukuttan A |title=Type 10 soluble adenylyl cyclase is overexpressed in prostate carcinoma and controls proliferation of prostate cancer cells |journal=J. Biol. Chem. |volume=288 |issue=5 |pages=3126–35 |date=February 2013 |pmid=23255611 |doi=10.1074/jbc.M112.403279 |display-authors=etal |pmc=3561535|doi-access=free }}</ref>
[[File:Hydrolisis of 3' cNMP phosphodiester bond by phosphodiesterase.png|thumb|Generic hydrolysis reaction of 3' cNMP phosphodiester bond by phosphodiesterase]]
Both cAMP and cGMP are degraded by [[hydrolysis]] of the 3' [[phosphodiester bond]], resulting in a 5'NMP.  Degradation is carried out primarily by a class of enzymes known as [[phosphodiesterase]]s (PDEs).  In mammalian cells, there are 11 known PDE families with varying [[Protein isoform|isoforms]] of each protein expressed based on the cell's regulatory needs.  Some phosphodiesterases are cNMP-specific, while others can hydrolyze non-specifically.<ref name="bender">{{cite journal |vauthors=Bender AT, Beavo JA |s2cid=7397281 |title=Cyclic nucleotide phosphodiesterases: molecular regulation to clinical use |journal=Pharmacol. Rev. |volume=58 |issue=3 |pages=488–520 |date=September 2006 |pmid=16968949 |doi=10.1124/pr.58.3.5 }}</ref> However, the cAMP and cGMP degradation pathways are much more understood than those for either cCMP or cUMP.  The identification of specific PDEs for cCMP and cUMP has not been as thoroughly established.<ref name="reineke">{{cite journal |vauthors=Reinecke D, Schwede F, Genieser HG, Seifert R |title=Analysis of substrate specificity and kinetics of cyclic nucleotide phosphodiesterases with N'-methylanthraniloyl-substituted purine and pyrimidine 3',5'-cyclic nucleotides by fluorescence spectrometry |journal=PLOS ONE |volume=8 |issue=1 |pages=e54158 |year=2013 |pmid=23342095 |pmc=3544816 |doi=10.1371/journal.pone.0054158 |bibcode=2013PLoSO...854158R |doi-access=free }}</ref>