SC4MOL/MSMO1 encodes a sterol-C4-methyl oxidase that catalyzes demethylation of C4-methylsterols in the cholesterol synthesis pathway; loss-of-function mutations cause an autosomal recessive syndrome with psoriasiform dermatitis, microcephaly, and developmental delay, with methylsterol accumulation.

MSMO1 protein-protein interactions are reported from the genome-scale HuRI binary interactome map; the individual partners are high-throughput hits rather than characterized functional complexes.

The human MSMO1 gene was identified as a homologue of yeast ERG25 (methyl sterol oxidase); the protein is membrane bound and immunofluorescence placed it in the endoplasmic reticulum (and plasma membrane).