The BMP-15 gene is located on the X-chromosome and using Northern blot analysis BMP-15 mRNA is locally expressed within the ovaries in oocytes only after they have started to undergo the primary stages of development. BMP-15 is translated as a preproprotein that is composed of a single peptide, which contains a proregion and a smaller mature region. Intracellular processing then leads to the removal of the proregion, leaving the biologically active mature region to perform the functions. This protein is a member of the Transforming growth factor beta (TGF-β) superfamily and is a paracrine signalling molecule. Most active BMPs have a common structure, in which they contain 7 cysteines, 6 of which form three intramolecular disulphide bonds and the seventh being involved in the formation of dimers with other monomers. BMP-15 is an exception to this as the molecule does not contain the seventh cysteine. Instead in BMP-15 the fourth cysteine is replaced by a serine.
