A lipid oxidation process proceeding through a series of three successive monooxygenations of the alpha methyl group on the C4 carbon (CH3 to CH2OH to CHO to COOH) and resulting in this overall reaction: 4-alpha-methyl-delta7-sterol + 3 NADPH + 3 H+ + 3 O2 = 4-alpha-carboxy,delta7-sterol + 3 NADP+ + 3 H2O.
4-alpha-methyl-delta7-sterol-4alpha-methyl oxidase activity