In ovary, it localizes to the theca cells of pre-antral follicles, the theca and granulosa cells of pre-ovulatory and ovulatory follicles, as well as to the developing corpus luteum. Increases around the time of ovulation and remained elevated in the developing corpus luteum. Expression is progesterone-dependent regulation prior to follicle rupture. Belongs to the peptidase S1 family. Although related to peptidase S1 family, lacks the conserved active Ser residue in position 342 which is replaced by a Thr, suggesting that it has no protease activity.