IUBMB Enzyme Nomenclature


Accepted name: dihydroceramide fatty acyl 2-hydroxylase

Reaction: a dihydroceramide + 2 ferrocytochrome b5 + O2 + 2 H+ = a (2'R)-2'-hydroxydihydroceramide + 2 ferricytochrome b5 + H2O

Glossary: a dihydroceramide = an N-acylsphinganine

Other name(s): FAH1 (gene name); FAH2 (gene name); plant sphingolipid fatty acid 2-hydroxylase

Systematic name: dihydroceramide,ferrocytochrome-b5:oxygen oxidoreductase (fatty acyl 2-hydroxylating)

Comments: The enzyme, characterized from plants, catalyses the hydroxylation of carbon 2 of long- or very-long-chain fatty acids attached to sphinganine during de novo ceramide synthesis. The enzyme requires an external cytochrome b5 as the electron donor. The newly introduced 2-hydroxyl group has R-configuration. cf. EC, 4-hydroxysphinganine ceramide fatty acyl 2-hydroxylase.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number:


1. Nagano, M., Ihara-Ohori, Y., Imai, H., Inada, N., Fujimoto, M., Tsutsumi, N., Uchimiya, H. and Kawai-Yamada, M. Functional association of cell death suppressor, Arabidopsis Bax inhibitor-1, with fatty acid 2-hydroxylation through cytochrome b5. Plant J. 58 (2009) 122-134. [PMID: 19054355]

2. Nagano, M., Takahara, K., Fujimoto, M., Tsutsumi, N., Uchimiya, H. and Kawai-Yamada, M. Arabidopsis sphingolipid fatty acid 2-hydroxylases (AtFAH1 and AtFAH2) are functionally differentiated in fatty acid 2-hydroxylation and stress responses. Plant Physiol. 159 (2012) 1138-1148. [PMID: 22635113]

3. Nagano, M., Uchimiya, H. and Kawai-Yamada, M. Plant sphingolipid fatty acid 2-hydroxylases have unique characters unlike their animal and fungus counterparts. Plant Signal Behav 7 (2012) 1388-1392. [PMID: 22918503]

[EC created 2015]

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