The two fungal enzymes, C-14 sterol reductase (gene ERG24 in budding yeast and erg3 in
Neurospora Crassa) and C-24(28) sterol reductase (gene ERG4 in budding yeast and sts1
in fission yeast), are involved in ergosterol biosynthesis. They act by reducing
double bonds in precursors of ergosterol [1].
These proteins are highly hydrophobic and seem to contain seven or eight transmembrane
regions. Chicken lamin B receptor that is thought to anchor the lamina to the inner
nuclear membrane belongs to this family.