ID 1.14.18.9 DE 4alpha-methylsterol monooxygenase. AN 4-methylsterol oxidase. AN methylsterol hydroxylase. AN methylsterol monooxygenase. CA 4,4-dimethyl-5alpha-cholest-7-en-3beta-ol + 6 Fe(II)-[cytochrome b5] + CA 5 H(+) + 3 O2 = 4alpha-carboxy-4beta-methyl-5alpha-cholest-7-ene-3beta-ol CA + 6 Fe(III)-[cytochrome b5] + 4 H2O. CC -!- This enzyme is found in fungi and animals and catalyzes a step in the CC biosynthesis of important sterol molecules such as ergosterol and CC cholesterol, respectively. CC -!- The enzyme acts on the 4alpha-methyl group. CC -!- Subsequent decarboxylation by EC 1.1.1.170 occurs concomitantly with CC epimerization of the remaining 4beta-methyl into the 4alpha position, CC thus making it a suitable substrate for a second round of catalysis. CC cf. EC 1.14.13.246, EC 1.14.18.10 and EC 1.14.18.11. CC -!- Formerly EC 1.14.13.72 and EC 1.14.99.16. DR O59933, ERG25_CANAL; Q5ZLL6, MSMO1_CHICK; Q7ZW77, MSMO1_DANRE; DR Q15800, MSMO1_HUMAN; Q4R4Q4, MSMO1_MACFA; Q9CRA4, MSMO1_MOUSE; DR Q6UGB2, MSMO1_PIG ; Q5R574, MSMO1_PONAB; O35532, MSMO1_RAT ; DR Q55D52, MSMOA_DICDI; Q55D54, MSMOB_DICDI; Q8L7W5, SMO11_ARATH; DR Q1EC69, SMO12_ARATH; F4JLZ6, SMO13_ARATH; Q9ZW22, SMO21_ARATH; DR Q8VWZ8, SMO22_ARATH; //