Interaction of Phe
of Angiotensin II with Lys
and His
of AT
Receptor in Agonist Activation (*)
- From the Department of Molecular Cardiology, Research Institute, The Cleveland Clinic Foundation, Cleveland, Ohio 44195-5069
- § To whom correspondence should be addressed: Dept. of Molecular Cardiology, Research Institute, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH 44195. Tel.: 216-444-1269; Fax: 216-444-9263.
Abstract
The acidic pharmacophores of selective ligands bind to Lys
and His
of the AT
receptor (Noda, K., Saad, Y., Kinoshita, A., Boyle, T. P., Graham, R. M., Husain, A., and Karnik, S.(1995) J. Biol. Chem. 270, 2284-2289). In this report we examine how interactions between these residues and agonists activate inositol phosphate
production in transiently transfected COS-1 cells. [Sar
] angiotensin (Ang II) II and [Sar
]Ang II-amide stimulated a 5-fold inositol phosphate response from wild-type AT
receptor. The peptide antagonist [Sar
,Ile
]Ang II and the non-peptide agonist L-162,313 produced a partial but saturating response. Stimulation of wild-type receptor
by [Sar
]Ang II-amide and the mutant K199Q and K199A receptors by [Sar
]Ang II demonstrates that AT
receptor activation is not critically dependent on the ion-pairing of the α-COOH group of Ang II with Lys
. The mutation of His
produced diminished inositol phosphate response without commensurate change in binding affinity of ligands. The His
side chain is critical for maximal activation of the AT
receptor, although isosteric Gln substitution is sufficient for preserving the affinity for Phe
-substituted analogues of [Sar
]Ang II. Therefore, AT
receptor activation requires interaction of Phe
side chain of Ang II with His
, which is achieved by docking the α-COOH group of Phe
to Lys
. Furthermore, non-peptide agonists interact with Lys
and His
in a similar fashion.
Footnotes
-
↵(*) This work was supported in part by Specialized Center of Research in Hypertension Grant HL33713 from the National Institutes of Health, a grant-in-aid from the American Heart Association/Northeast Ohio Affiliate Inc. (HANEO), and a HANEO fellowship (to K. N.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
-
↵1 The abbreviations used are:
- Ang II or AII
-
the octapeptide hormone angiotensin II, NH
-D-R-V-Y-I-H-P-F-COOH
- L-162,163
-
[5,7-dimethyl-2-ethyl-3-[(4-[2(n-butyloxycarbonylsulfonamido)-isobutyl-thienyl]] phenyl]methylimidazol[4,5,6]pyridine (22)
- IP
-
inositol phosphate
- HBSS
-
Hanks' balanced salt solution.
-
↵2 S. Sung and S. Karnik, unpublished observations.
-
- Received September 21, 1995.
- Revision received October 4, 1995.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
