'Decoy peptide' region (RIFLKRMPSI) of prorenin prosegment plays a crucial role in prorenin binding to the (pro)renin receptor

This Study investigated a role of decoy peptide region ((RIFLKRMPSI19P)-I-10P) in prorenin prosegment for prorenin binding to the (pro)renin receptor using the surface plasmon resonance technique. Three kinds of anti-receptor antibodies labeled as anti-107/121, anti-221/235 and anti-His tag antibody were prepared. The respective antigens D(107)SVANSIHSLFSEET(121) (close to the N-terminal side of receptor), E(221)IGKRYGEDSEQFRD(235) (N-terminal side of the transmembrane part of receptor) and 10xHis sequence (C-terminus) were designed based on the sequence of the receptor. These antibodies were immobilized on the CM5 sensor chip by amine coupling and allowed to bind to the receptor. Human prorenin, renin and the decoy bound to the receptor associated with antibodies. Their association (k(a)) and dissociation (k(d)) rate constants were measured and the dissociation constants (K-D) were determined using Langmuir 1:1 kinetic binding model. The K-D for interaction of prorenin and receptor associated to anti-107/121, anti-221/235 and anti-His tag antibodies were 2.9, 1.2 and 7.8 nM, respectively and for renin they were 9.3, 4.4 and 7.1 nM. The decoy bound to the respective immobilized receptor-anti body complexes at K-D's of 6.2, 3.5 and 15.2 nM. Prorenin, renin and decoy had lower K-D at the nanomolar ranges compared to those of (LTD4P)-T-1P in the prorenin prosegment and A(248)KKRLFDYVV(257) in the C-domain of mature renin. The decoy reduced the binding of not only prorenin but also renin to (P)RR. These data are direct evidence that prorenin, renin and the peptides bind to (P)RR and the decoy reduces prorenin binding, supporting our hypothesis that decoy peptide region has a Crucial role in prorenin binding.