Editing Squalene (section)

==Role in triterpenoid synthesis==
Squalene is a biochemical precursor to both [[steroids]] and [[hopanoids]].<ref>{{cite journal|last=Bloch|first=Konrad E.|title=Sterol, Structure and Membrane Function|journal=[[Critical Reviews in Biochemistry and Molecular Biology]]|year=1983|volume=14|issue=1|pages=47–92|doi=10.3109/10409238309102790|pmid=6340956}}</ref> For sterols, the squalene conversion begins with oxidation (via [[squalene monooxygenase]]) of one of its terminal double bonds, resulting in [[2,3-oxidosqualene]]. It then undergoes an enzyme-catalysed cyclisation to produce [[lanosterol]], which can be elaborated into other steroids such as [[cholesterol]] and [[ergosterol]] in a multistep process by the removal of three methyl groups, the reduction of one double bond by [[NADPH]] and the migration of the other double bond.<ref>{{cite journal |last1=Cerqueira |first1=Nuno M. F. S. A. |last2=Oliveira |first2=Eduardo F. |last3=Gesto |first3=Diana S. |last4=Santos-Martins |first4=Diogo |last5=Moreira |first5=Cátia |last6=Moorthy |first6=Hari N. |last7=Ramos |first7=Maria J. |last8=Fernandes |first8=P. A. |title=Cholesterol Biosynthesis: A Mechanistic Overview |journal=Biochemistry |date=4 October 2016 |volume=55 |issue=39 |pages=5483–5506 |doi=10.1021/acs.biochem.6b00342|pmid=27604037 }}</ref> In many plants, this is then converted into [[stigmasterol]], while in many fungi, it is the precursor to [[ergosterol]].{{cn|date=July 2023}}
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The biosynthetic pathway is found in many bacteria,<ref>{{cite journal |last1=Rohmer |first1=M. |last2=Bouvier-Nave |first2=P. |last3=Ourisson |first3=G. |title=Distribution of Hopanoid Triterpenes in Prokaryotes |journal=Microbiology |date=1 May 1984 |volume=130 |issue=5 |pages=1137–1150 |doi=10.1099/00221287-130-5-1137|doi-access=free }}</ref> and most [[eukaryotes]], though has not been found in Archaea.<ref>{{cite journal |last1=Santana-Molina |first1=Carlos |last2=Rivas-Marin |first2=Elena |last3=Rojas |first3=Ana M |last4=Devos |first4=Damien P |title=Origin and Evolution of Polycyclic Triterpene Synthesis |journal=Molecular Biology and Evolution |date=1 July 2020 |volume=37 |issue=7 |pages=1925–1941 |doi=10.1093/molbev/msaa054|pmid=32125435 |pmc=7306690 }}</ref>