Bradykinin signaling

B2 knockout embryos subjected to salt stress in utero show suppressed renin expression and an abnormal kidney phenotype and develop early postnatal hypertension. Consistently, although basal bradykinin formation is defective tissue kallikrein-null mice have normal blood pressure however suffer from cardiovascular abnormalities. However suggesting a function of kinin signaling during development. 

Other actions of kinins include activation of clotting factors simultaneously with the production of bradykinin. In the kidney, bradykinin production results in an increase in renal papillary blood flow, with a secondary inhibition of sodium reabsorption in the distal tubule. In the peripheral nervous system, bradykinin is important for the initiation of pain signals. It is also associated with the edema, erythema, and fever of inflammation. 

The bradykinin receptor is a member of a family of receptors for which an intracellular interaction with a G-protein is a critical part of the signal transduction pathway following agonist binding. Structurally, these G-protein-coupled receptors extend from beyond the extracellular boundary of the cell membrane into the cytoplasm. The tertiary structure is such that the protein crosses the bilayer of the cell membrane seven times, thus forming three intracellular loops, three extracellular loops, and giving rise to cytoplasmic C-terminal and extra-cellular N-terminal strands. It is generally presumed that the transmembrane domains of these receptors exist as a bundle of helical strands. This assumption is derived primarily from the known structure of the trans-membrane portions of a structurally related protein, bacteriorhodopsin [40]. 

Albert O, Ancellin N, Preisser L, Morel A, Corman B. Serotonin, bradykinin and endothelin signalling in a sheep choroid plexus cell line. Life Sci 1999 64 859-867. 

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