Editing Quaternary ammonium cation (section)

==Natural occurrence==
Several quaternary ammonium derivatives exist in nature.<ref>{{cite journal |doi=10.1016/0305-0491(91)90002-U|title=Quaternary ammonium compounds in the biosphere—An Example of a Versatile Adaptive Strategy |year=1991 |last1=Anthoni |first1=U. |last2=Christophersen |first2=C. |last3=Hougaard |first3=L. |last4=Nielsen |first4=P.H. |journal=Comparative Biochemistry and Physiology Part B: Comparative Biochemistry |volume=99 |pages=1–18 }}</ref>  Prominent examples include  [[glycine betaine]], [[choline]], [[carnitine]], butyrobetaine, [[homarine]], and [[trigonelline]]. Glycine betaine, an [[osmolyte]], stabilizes osmotic pressure in cells.<ref>{{cite journal  | doi = 10.1093/aob/mcu239 | title = Diversity, distribution and roles of osmoprotective compounds accumulated in halophytes under abiotic stress | year = 2015 | last1 = Slama | first1 = Inès | last2 = Abdelly | first2 = Chedly | last3 = Bouchereau | first3 = Alain | last4 = Flowers | first4 = Tim | last5 = Savouré | first5 = Arnould | journal = Annals of Botany | volume = 115 | issue = 3 | pages = 433–447 | pmid = 25564467 | pmc = 4332610 }}</ref>
[[File:Betain2.svg|thumb|150 px|[[Glycine betaine]] is a naturally occurring quaternary ammonium cation. Its degradation product, [[trimethylamine]], is responsible for the odor of spoiled fish.|left]]
[[Image:Choline-skeletal.svg|thumb|[[Choline]] is a quat compound.]]

Choline is a precursor for the neurotransmitter [[acetylcholine]]. Choline is also a constituent of [[lecithin]], which is present in many plants and animal organs.<ref name="Zeisel">{{cite journal | vauthors = Zeisel SH, da Costa KA | title = Choline: an essential nutrient for public health | journal = Nutrition Reviews | volume = 67 | issue = 11 | pages = 615–623 | date = November 2009 | pmid = 19906248 | pmc = 2782876 | doi = 10.1111/j.1753-4887.2009.00246.x | author-link = Steven Zeisel }}</ref>  It is found in [[phospholipid]]s. For example, [[phosphatidylcholines]], a major component of [[biological membrane]]s, are a member of the [[lecithin]] group of fatty substances in animal and plant tissues.<ref>{{cite book | vauthors = Jackowski S, Cronan Jr JE, Rock CO |chapter=Chapter 2: Lipid metabolism in procaryotes | veditors = Vance DE, Vance J  |title=Biochemistry of Lipids, Lipoproteins and Membranes |publisher=Elsevier |year=1991 |pages=[https://archive.org/details/biochemistryofli0000unse/page/80 80–81]  |isbn=0-444-89321-0 |chapter-url-access=registration |chapter-url=https://archive.org/details/biochemistryofli0000unse |url=https://archive.org/details/biochemistryofli0000unse/page/80 }}</ref>

[[Carnitine]] participates in the [[beta-oxidation]] of fatty acids.{{cn|date=August 2023}}

[[File:1-Oleoyl-2-almitoyl-phosphatidylcholine Structural Formulae V.1.png|thumb|right|1-Oleoyl-2-palmitoyl-phosphatidylcholine]]