label: C20 sphinganine + 2 Fe(II)-[cytochrome b5] + O2 + 2 H(+) = (4R)-hydroxyeicosasphinganine + 2 Fe(III)-[cytochrome b5] + H2O
label_lc: c20 sphinganine + 2 fe(ii)-[cytochrome b5] + o2 + 2 h(+) = (4r)-hydroxyeicosasphinganine + 2 fe(iii)-[cytochrome b5] + h2o