Lanosterol 14alpha-demethylase (CYP51) and spermatogenesis.

CYP51 is the only gene of the cytochrome P450 (P450, or CYP) superfamily that is expressed in prokaryotes and eukaryotes. In animals, the gene product, P45014DM, catalyzes the lanosterol 14alpha-demethylase reaction, an essential step in cholesterol biosynthesis. P45014DM serves a housekeeping role, and it was surprising to find the highest level of CYP51 expression in the testes. This is a result of very high-level CYP51 expression in postmeiotic, haploid spermatids and results in elevated P45014DM activity in these cells. It is proposed that the elevated level of 14alpha-demethylase activity leads to production of signaling sterols by haploid germ cells, although the function of such sterols in males is unknown.