Structure of two fragments of the third cytoplasmic loop of the rat angiotensin II AT(1A) receptor

Structure of two fragments of the third cytoplasmic loop of the rat angiotensin II AT(1A) receptor

Autor Franzoni, Lorella Google Scholar
Nicastro, Giuseppe Google Scholar
Pertinhez, Thelma A. Google Scholar
Oliveira, Eliandre Autor UNIFESP Google Scholar
Nakaie, Clovis Ryuichi Autor UNIFESP Google Scholar
Paiva, Antonio Cechelli de Mattos Autor UNIFESP Google Scholar
Schreier, Shirley Google Scholar
Spisni, Alberto Google Scholar
Instituição Univ Parma
Universidade de São Paulo (USP)
Universidade Federal de São Paulo (UNIFESP)
Resumo The structural bases that render the third intracellular loop (i3) of the rat angiotensin II AT,, receptor one of the cytoplasmic domains responsible for G-protein coupling are still unknown, the three-dimensional structures of two overlapping peptides mapping the entire i3 loop and shown to differently interact with purified G-proteins have been obtained by simulated annealing calculations, using NMR-derived constraints collected in 70% water/30% trifluoroethanol solution, While the NH2-terminal half, Ni3, residues 213-231, adopts a stable amphipathic alpha-helix, extending over almost the entire peptide, a more flexible conformation is found for the COOH-terminal half, Ci3, residues 227-242, for this peptide, a cis-trans isomerization around the Lys(6)-Pro(7) peptide bond generates two exchanging isomers adopting similar conformations, with an ct-helix spanning from Asn(9) to Ile(15) and a poorly defined NH, terminus. A quite distinct structural organization is found for the sequence EIQKN, common to Ni3 and Ci3, the data do suggest that the extension and orientation of the amphipathic cu-helix, present in the proximal part of i3, may be modulated by the distal part of the loop itself through the Pro(233) residue. A molecular model where this possibility is considered as a mechanism for G-protein selection and coupling is presented.
Idioma Inglês
Data de publicação 1999-01-01
Publicado em Journal of Biological Chemistry. Bethesda: Amer Soc Biochemistry Molecular Biology Inc, v. 274, n. 1, p. 227-235, 1999.
ISSN 0021-9258 (Sherpa/Romeo, fator de impacto)
Publicador Amer Soc Biochemistry Molecular Biology Inc
Extensão 227-235
Direito de acesso Acesso aberto Open Access
Tipo Artigo
Web of Science WOS:000077900200034
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