Unexpected binding of an octapeptide to the angiotensin II receptor
An octapeptide, TBI-22 (Lys-Gly-Val-Tyr-Ile, His-Ala-Leu), inhibited binding of angiotensin II by a solubilized angiotensin receptor partially purified from rabbit liver. This inhibition appears to result from competition for binding to the same receptor. Radioiodinated TBI-22, like angiotensin II, bound to the solubilized receptor with an affinity such that the binding was inhibited 50% by unlabeled TBI-22 or angiotensin II at nanomolar concentrations. The binding reaction, like that for angiotensin II, required p-chloromercuriphenylsulfonic acid and was reversed in the presence of dithiothreitol. TBI-22 and angiotensin II share the sequence Val-Tyr-Ile-His; this tetrapeptide alone, however, did not inhibit binding of angiotensin II. Replacement of the tyrosine residue by aspartic acid in TBI-22 greatly reduced the ability of the peptide to compete with angiotensin II for binding, suggesting an important contribution of this residue to the configuration required for recognition by the receptor.
- Research Organization:
- Cornell Univ. Medical College, New York, NY (USA)
- OSTI ID:
- 6271555
- Journal Information:
- Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 84:24
- Country of Publication:
- United States
- Language:
- English
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550201* - Biochemistry- Tracer Techniques