furin (Paired Basic Amino acid residue-Cleaving Enzyme {PACE}, kexin homolog, paired-basic endopeptidase, prohormone-processing endoprotease, serine proteinase homolog fur)

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Function

ubiquitous endoprotease within constitutive secretory pathways
capable of cleavage at the RX(K/R)R consensus motif
interacts with FLNA (putative)
binds to PACS1 which mediates TGN localization & connection to clathrin adapters
could be inhibited by the not secondly cleaved propeptide; the inhibition peptide, which plays the role of an intramolecular chaperone, is autocatalytically removed in the endoplasmic reticulum (ER) & remains non-covalently bound to furin as a potent autoinhibitor; following transport to the trans Golgi, a second cleavage within the inhibition propeptide results in propeptide dissociation & furin activation
phosphorylation is required for TGN localization of the endoprotease.
in vivo, exists as di-, mono- & non-phosphorylated forms
release of mature proteins from their proproteins by cleavage of -Arg-Xaa-Yaa-Arg-|-Zaa- bonds, where Xaa can be any amino acid & Yaa is Arg or Lys
releases albumin, complement component C3 & von Willebrand factor from their respective precursors

contains a cytoplasmic domain responsible for its TGN localization & recycling from the cell surface
belongs to the peptidase S8 family, Furin subfamily
contains 1 homo B/P domain

Golgi, trans-Golgi network membrane
cell membrane
shuttles between the trans-Golgi network & the cell surface
propeptide cleavage is a prerequisite for exit of furin molecules out of the endoplasmic reticulum (ER, a second cleavage within the propeptide occurs in the trans Golgi network (TGN), followed by the release of the propeptide & activation of furin

seems to be expressed ubiquitously