Accepted name: squalene methyltransferase
Reaction: 2 S-adenosyl-L-methionine + squalene = 2 S-adenosyl-L-homocysteine + 3,22-dimethyl-1,2,23,24-tetradehydro-2,3,22,23-tetrahydrosqualene (overall reaction)
(1a) S-adenosyl-L-methionine + squalene = S-adenosyl-L-homocysteine + 3-methyl-1,2-didehydro-2,3-dihydrosqualene
(1b) S-adenosyl-L-methionine + 3-methyl-1,2-didehydro-2,3-dihydrosqualene = S-adenosyl-L-homocysteine + 3,22-dimethyl-1,2,23,24-tetradehydro-2,3,22,23-tetrahydrosqualene
Other name(s): TMT-1; TMT-2
Systematic name: S-adenosyl-L-methionine:squalene C-methyltransferase
Comments: Two isoforms differing in their specificity were isolated from the green alga Botryococcus braunii BOT22. TMT-1 gave more of the dimethylated form whereas TMT2 gave more of the monomethylated form.
1.  Niehaus, T.D., Kinison, S., Okada, S., Yeo, Y.S., Bell, S.A., Cui, P., Devarenne, T.P. and Chappell, J. Functional identification of triterpene methyltransferases from Botryococcus braunii race B. J. Biol. Chem. 287 (2012) 8163–8173. [PMID: 22241476]
[EC created 2012]

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