ExplorEnz: EC 2.1.1.406

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2.1.1.406

Accepted name:

sterol 4-C-methyltransferase

Reaction:

5α-cholest-7-en-3-one + S-adenosyl-L-methionine = 4α-methyl-5α-cholest-7-en-3-one + S-adenosyl-L-homocysteine

Glossary:

lathosterone = 5α-cholest-7-en-3-one
lophenol = 4α-methyl-5α-cholest-7-en-3-one

Other name(s):

4-SMT; STRM-1

Systematic name:

S-adenosyl-L-methionine:3-oxosterol 4-C-methyltransferase

Comments:

The enzyme occurs in larvae of Caenorhabditis elegans. The reaction mechanism of C-4-methyl sterol formation is a two-step process of bound 3-oxo sterol undergoing active site isomerization to the 4-enol intermediate that is methylated by SAM in a stereoselective manner to yield the the equatorial 4α-methyl group, followed by rearrangement of the enol back to the 3-oxo form. The enzyme converts lathosterone to lophenol. Other substrates are cholest-4-en-3-one, cholest-5-en-3-one, and cholestanone.

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc

References:

1.	Hannich, J.T., Entchev, E.V., Mende, F., Boytchev, H., Martin, R., Zagoriy, V., Theumer, G., Riezman, I., Riezman, H., Knolker, H.J. and Kurzchalia, T.V. Methylation of the sterol nucleus by STRM-1 regulates dauer larva formation in Caenorhabditis elegans. Dev. Cell 16 (2009) 833–843. [DOI] [PMID: 19531354]
2.	Zhou, W., Fisher, P.M., Vanderloop, B.H., Shen, Y., Shi, H., Maldonado, A.J., Leaver, D.J. and Nes, W.D. A nematode sterol C4α-methyltransferase catalyzes a new methylation reaction responsible for sterol diversity. J. Lipid Res. 61 (2020) 192–204. [DOI] [PMID: 31548366]

[EC 2.1.1.406 created 2025]