Serine endoprotease that processes various proproteins by cleavage at paired basic amino acids, recognizing the RXXX[KR]R consensus motif. Likely functions in the constitutive and regulated secretory pathways. Plays an essential role in pregnancy establishment by proteolytic activation of a number of important factors such as BMP2, CALD1 and alpha-integrins. May be responsible for the maturation of gastrointestinal peptides. May be involved in the cellular proliferation of adrenal cortex via the activation of growth factors. Secreted through the regulated secretory pathway. Type I membrane protein localized to a paranuclear post-Golgi network compartment in communication with early endosomes. Additional isoforms seem to exist. Expressed in the intestine, brain, adrenal gland, anterior pituitary, thyroid, ovaries, testis and lung. Highest levels are found in the gut, duodenum, jejunum and ileum. Expression is higher in female than in male reproductive organs. First detected at E9 in highly restricted regions of the neural tube, in caudal myotomes, and at the materno-embryonic junction of the uterus. At E10, restricted expression is detected in the optic and otic vesicles, the roof of midbrain, and trunk myotomes. By midgestation (E13-E16), expression in the developing nervous system has expanded to multiple regions including hippocampus, thalamus, hypothalamus, brain stem, and spinal cord. Expression is also detected in several peripheral organ systems, including gut, lung, adrenal and kydney primordia. The propeptide domain acts as an intramolecular chaperone assisting the folding of the zymogen within the endoplasmic reticulum. AC 1 and AC 2 (clusters of acidic amino acids) contain sorting information. AC 1 directs TGN localization and interacts with the TGN sorting protein PACS-1. Belongs to the peptidase S8 family.