Mutation of Asn111 in the third transmembrane domain of the AT1A angiotensin II receptor induces its constitutive activation.
A preliminary model of the rat AT1A angiotensin II (AII) receptor (Joseph, M. P., Maigret, B., Bonnafous J.-C., Marie, J., and Scheraga, H. A. (1995) J. Protein Chem. 14, 381-398) has predicted an interaction between Asn111 located in transmembrane domain (TM) III and Tyr292 (TM VII) in the nonactivated receptor; a disruption of this interaction upon AII activation would allow Tyr292 to interact with the conserved Asp74 (TM II). The previous verification that Tyr292 is essential for receptor coupling to phospholipase C (Marie, J., Maigret, B., Joseph, M. P., Larguier, R., Nouet, S., Lombard, C., and Bonnafous, J.-C. (1994) J. Biol. Chem. 269, 20815-20818) prompted us to check the possible alterations in receptor properties upon Asn111 --> Ala mutation. The mutated receptor (N111A) displayed: (i) strong constitutive activity, with amplification of the maximal phospholipase C response to AII; (ii) agonist behavior of the AT2-specific ligand CGP 42112A, [Sar1, Ile8]AII, and [Sar1,Ala8]AII, antagonists of the wild-type receptor; (iii) inverse agonism behavior of the non-peptide ligands DuP 753, LF 7-0156, and LF 8-0129. The results are discussed in the light of the allosteric ternary complex models and other described examples of constitutive activation of G protein-coupled receptors.
Groblewski
T
T
INSERM U.401, CCIPE, 141 rue de la Cardonille, 34094 Montpellier Cedex 05, France.
Maigret
B
B
Larguier
R
R
Lombard
C
C
Bonnafous
J C
JC
Marie
J
J
D000409:Alanine / Q000235:genetics; D000818:Animals; D001216:Asparagine / Q000235:genetics*; D019556:COS Cells; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D051381:Rats; D011945:Receptors, Angiotensin / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism
D011945:Receptors, Angiotensin; D011994:Recombinant Proteins; D001216:Asparagine; D000409:Alanine