Metallopeptidases are enzymes that catalyze the hydrolysis of peptide bonds and are essential to normal physiological processes, including tissue remodeling, reproduction and embryonic development. FXNA (felix-ina), also known as ERMP1 (endoplasmic reticulum metallopeptidase 1) or KIAA1815, is a 904 amino acid metallopeptidase that belongs to the peptidase M28 protein family. FXNA is a multi-pass membrane protein that localizes to the endoplasmic reticulum membrane. FXNA binds two zinc ions and, within the ovary, is essential to the organization of oocytes and somatic cells into discrete follicular structures. The gene that encodes FXNA maps to human chromosome 9, which consists of about 145 million bases and encodes nearly 900 genes. Considered to play a role in gender determination, deletion of the distal portion of 9p can lead to development of male to female sex reversal, the phenotype of a female with a male X,Y genotype.