Definition:

A cytochrome P450 monooxygenase involved in epidermal ceramide biosynthesis. Hydroxylates the terminal carbon (omega-hydroxylation) of ultra-long-chain fatty acyls (C28-C36) prior to ceramide synthesis. Contributes to the synthesis of three classes of omega-hydroxy-ultra-long chain fatty acylceramides having sphingosine, 6-hydroxysphingosine and phytosphingosine bases, all major lipid components that underlie the permeability barrier of the stratum corneum. Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate, and reducing the second into a water molecule, with two electrons provided by NADPH via cytochrome P450 reductase (CPR; NADPH-ferrihemoprotein reductase).