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. In adults, isoform 1-CRR is expressed in CNS, fat body, and female reproductive tissues, and in embryos, in anal pads, hindgut, developing antennomaxillary complex, oenocytes, clipeolabrum, pharynx, trachea, CNS and developing posterior spiracles. Isoform 1-CRR is expressed in embryos, larvae, pupae and adults. Belongs to the peptidase S8 family. Furin subfamily.