The ERG28 gene was originally identified by microarray expression profiling as possibly involved in the Saccharomyces cerevisiae sterol pathway. Microarray analyses suggested that the transcription pattern of ERG28 closely followed that of genes involved in sterol synthesis. ERG28 was also found in Schizosaccharomyces pombe and Arabidopsis as well as humans, and in the latter was shown to be highly expressed in adult testis tissue. All four proteins contain potential transmembrane domain(s). Gas chromatography-mass spectrometry analysis of an ERG28-deleted S. cerevisiae strain (which is slow growing but not auxotrophic for ergosterol) indicates a lesion in sterol C-4 demethylation. Sterol profiles indicate accumulation of 3-keto and carboxylic acid sterol intermediates, which are involved in removing the two C-4 methyl groups from the sterol A ring. Similar intermediates have previously been demonstrated to accumulate in erg26 (sterol dehydrogenase/decarboxylase) and erg27 (3-ketoreductase) mutants in yeast. We speculate that the role of the Erg28 protein (Erg28p) may be either to tether Erg26p and Erg27p to the endoplasmic reticulum or to facilitate interaction between these proteins.-Gachotte, D., J. Eckstein, R. Barbuch, T. Hughes, C. Roberts, and M. Bard. A novel gene conserved from yeast to humans is involved in sterol biosynthesis. J. Lipid Res. 2001. 42: 150;-154.