B-type (Brain) natriuretic peptide (BNP) is a 32 amino acid hormone initially isolated from the porcine brain, but mainly produced by the heart ventricles. It is released from a prepro-hormone after cleavage of a signal peptide and further processing by a protease with a conserved recognition sequence (RXXR-S). This cleavage generated NT-proBNP (76aa) and the biologically active 32aa BNP-32, which are secreted in blood in equimolar concentrations.
BNP-32 is secreted by cardiomyocytes in response to myocardial stretch and overload resulting from hypervolaemia and increased blood pressure. It is known to oppose the renin-angiotensin-aldosterone system and exert vasodilatory effects. This 32 amino acid peptide contains a 17 amino acid ring structure that is common to all natriuretic peptides.