|Accepted name:||ultra-long-chain fatty acid ω-hydroxylase|
|Reaction:||an ultra-long-chain fatty acid + [reduced NADPH—hemoprotein reductase] + O2 = an ultra-long-chain ω-hydroxy fatty acid + [oxidized NADPH—hemoprotein reductase] + H2O|
|Other name(s):||CYP4F22 (gene name)|
|Systematic name:||ultra-long-chain fatty acid,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (ω-hydroxylating)|
|Comments:||The enzyme, which is expressed in the epidermis of mammals, catalyses the ω-hydroxylation of ultra-long-chain fatty acids (C28 to C36). The products are incorporated into acylceramides, epidermis-specific ceramide species that are very important for skin barrier formation.|
|Accepted name:||ω-hydroxyceramide transacylase|
|Reaction:||a linoleate-containing triacyl-sn-glycerol + an ultra-long-chain ω-hydroxyceramide = a diacyl-sn-glycerol + a linoleate-esterified acylceramide|
|Glossary:||an ultra-long-chain fatty acid = ULCFA = a fatty acid with aliphatic chain of 28 or more carbons
an ultra-long-chain ω-hydroxyceramide = a ceramide that contains an ultra-long-chain ω-hydroxyfatty acid moiety (C28-C36)
acylceramide = ω-O-acylceramide = a ceramide that contains an ultra-long-chain ω-hydroxyfatty acid moiety (C28-C36) that is further extended by ω-esterification with linoleic acid.
|Other name(s):||PNPLA1 (gene name)|
|Systematic name:||triacyl-sn-glycerol:ultra-long-chain ω-hydroxyceramide ω-O-linoleoyltransferase|
|Comments:||The enzyme participates in the production of acylceramides in the stratum corneum, the outermost layer of the epidermis. Acylceramides are crucial components of the skin permeability barrier.|
|Accepted name:||ultra-long-chain ceramide synthase|
|Reaction:||an ultra-long-chain fatty acyl-CoA + a sphingoid base = an ultra-long-chain ceramide + CoA|
|Glossary:||a sphingoid base = an amino alcohol, composed predominantly of 18 carbon atoms, characterized by the presence of a hydroxyl group at C-1 (and often also at C-3), and an amine group at C-2.
an ultra-long-chain fatty acyl-CoA = an acyl-CoA with a chain length of 28 or longer.
|Other name(s):||mammalian ceramide synthase 3; sphingoid base N-ultra-long-chain fatty acyl-CoA transferase; CERS3 (gene name)|
|Systematic name:||ultra-long-chain fatty acyl-CoA:sphingoid base N-acyltransferase|
|Comments:||Mammals have six ceramide synthases that exhibit relatively strict specificity regarding the chain-length of their acyl-CoA substrates. Ceramide synthase 3 (CERS3) is the only enzyme that is active with ultra-long-chain acyl-CoA donors (C28 or longer). It is active in the epidermis, where its products are incorporated into acylceramides. CERS3 also accepts (2R)-2-hydroxy fatty acids and ω-hydroxy fatty acids, and can accept very-long-chain acyl-CoA substrates (see EC 126.96.36.1997, very-long-chain ceramide synthase). It can use multiple sphingoid bases including sphinganine, sphingosine, phytosphingosine, and (6R)-6-hydroxysphingosine.|