Involved in the processing of hormone and other protein precursors at sites comprised of pairs of basic amino acid residues. Substrates include POMC, renin, enkephalin, dynorphin, somatostatin, insulin and AGRP. Release of protein hormones, neuropeptides and renin from their precursors, generally by hydrolysis of -Lys-Arg-|- bonds. Localized in the secretion granules. Belongs to the peptidase S8 family. Furin subfamily.