Fatty acid 2-hydroxylase involved in the alpha-hydroxylation of sphingolipid-associated very long-chain fatty acids (VLCFA). Probably involved in the resistance response to oxidative stress. an N-(1,2-saturated acyl)sphinganine + 2 Fe(II)-[cytochrome b5] + 2 H(+) + O2 = an N-[(2'R)-hydroxyacyl]sphinganine + 2 Fe(III)-[cytochrome b5] + H2O Binds 2 Zn(2+) ions per subunit that likely form a catalytic dimetal center. Interacts with CYTB5-A, CYTB5-B, CYTB5-C and CYTB5-D. Interacts indirectly with BI-1 via CYTB5-D. Expressed in leaves, roots, flowers and seeds. Up-regulated by H(2)O(2) treatment. Belongs to the sterol desaturase family.