Furin is likely to represent the ubiquitous endoprotease activity within constitutive secretory pathways and capable of cleavage at the RX(K/R)R consensus motif. Release of mature proteins from their proproteins by cleavage of -Arg-Xaa-Yaa-Arg-|-Zaa- bonds, where Xaa can be any amino acid and Yaa is Arg or Lys. Releases albumin, complement component C3 and von Willebrand factor from their respective precursors. Transient expression in a subset of central nervous system neurons during embryonic stages 12-13. Expression in developing tracheal tree from stage 13 to end of embryonic development. Expressed both maternally and zygotically. Belongs to the peptidase S8 family. Furin subfamily. Intron retention.