Bradykinin-related peptide family
, a 9 amino-acid peptide, is a potent endothelium-dependent vasodilator that causes contraction of non-vascular smooth muscle, increases vascular permeability and is involved in the mechanism of pain. Bradykinin also causes
, contributing to a drop in blood pressure.
Bradykinin is proteolytically cleaved from its kininogen precursor by the enzyme kallikrein.
Bradykinin is broken down by three kininases:
angiotensin-converting enzyme (ACE)
, aminopeptidase P (APP), and carboxypeptidase N (CPN), which cleave the 7-8, 1-2, and 8-9 positions, respectively.
Bradykinin has two receptors, the bradykinin
receptors that belong to G protein coupled receptor (GPCR) family. The B1 receptor is expressed only as a result of tissue injury, and is presumed to play a role in chronic pain. This receptor has been also described to play a role in inflammation. The B2 receptor is constitutively expressed and participates in bradykinin's vasodilatory role.
Bradykinin-related peptides in venom
Several bradykinin-related peptides have been described in spider and insect venoms (see the right box), as well as in amphibian skin secretions (see proteins
Liberation of endogenous bradykinin by venom serine proteases
Endogenous bradykinin can also be generated by the action of venom serine proteases (see proteins with this action
, and the serine protease description file
This protein family in
SIB Swiss Institute of Bioinformatics