InterPro domain: IPR006716

This family consists of the fungal C-8 sterol isomerase and mammalian sigma1 receptor. C-8 sterol isomerase (delta-8--delta-7 sterol isomerase), catalyses a reaction in ergosterol biosynthesis, which results in unsaturation at C-7 in the B ring of sterols [ 1 ]. Sigma 1 receptor is a low molecular mass mammalian protein located in the endoplasmic reticulum [ 2 ], which interacts with endogenous steroid hormones, such as progesterone and testosterone [ 3 ]. It also binds the sigma ligands, which are a set of chemically unrelated drugs including haloperidol, pentazocine, and ditolylguanidine [ 4 ]. Sigma1 effectors are not well understood, but sigma1 agonists have been observed to affect NMDA receptor function, the alpha-adrenergic system and opioid analgesia.

1. Isolation of the ERG2 gene, encoding sterol delta 8-->delta 7 isomerase, from the rice blast fungus Magnaporthe grisea and its expression in the maize smut pathogen Ustilago maydis. Curr. Genet. 25, 531-7
2. Purification, molecular cloning, and expression of the mammalian sigma1-binding site. Proc. Natl. Acad. Sci. U.S.A. 93, 8072-7
3. Cloning and structural analysis of the cDNA and the gene encoding the murine type 1 sigma receptor. Biochem. Biophys. Res. Commun. 241, 535-40