Fatty acid 2-hydroxylase involved in the alpha-hydroxylation of the long-chain fatty acid (LCFA) palmitic acid. 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. Expressed in leaves, roots, flowers and seeds. Not induced by H(2)O(2) treatment. No visible phenotype under normal growth conditions. Belongs to the sterol desaturase family.