Abstract
The structural bases that render the third intracellular loop (i3) of the rat angiotensin II AT(1A) 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 α-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 Lys6-Pro7 peptide bond generates two exchanging isomers adopting similar conformations, with an α-helix spanning from Asn9 to Ile15 and a poorly defined NH2 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 α-helix, present in the proximal part of i3, may be modulated by the distal part of the loop itself through the Pro233 residue. A molecular model where this possibility is considered as a mechanism for G-protein selection and coupling is presented.
| Original language | English |
|---|---|
| Pages (from-to) | 227-235 |
| Number of pages | 9 |
| Journal | Journal of Biological Chemistry |
| Volume | 274 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Jan 1 1999 |
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ASJC Scopus subject areas
- Biochemistry
Cite this
Structure of two fragments of the third cytoplasmic loop of the rat angiotensin II AT(1A) receptor : Implications with respect to receptor activation and G-protein selection and coupling. / Franzoni, Lorella; Nicastro, Giuseppe; Pertinhez, Thelma A.; Oliveira, Eliandre; Nakaie, Clóvis R.; Paiva, Antonio C M; Schreier, Shirley; Spisni, Alberto.
In: Journal of Biological Chemistry, Vol. 274, No. 1, 01.01.1999, p. 227-235.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Structure of two fragments of the third cytoplasmic loop of the rat angiotensin II AT(1A) receptor
T2 - Implications with respect to receptor activation and G-protein selection and coupling
AU - Franzoni, Lorella
AU - Nicastro, Giuseppe
AU - Pertinhez, Thelma A.
AU - Oliveira, Eliandre
AU - Nakaie, Clóvis R.
AU - Paiva, Antonio C M
AU - Schreier, Shirley
AU - Spisni, Alberto
PY - 1999/1/1
Y1 - 1999/1/1
N2 - The structural bases that render the third intracellular loop (i3) of the rat angiotensin II AT(1A) 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 α-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 Lys6-Pro7 peptide bond generates two exchanging isomers adopting similar conformations, with an α-helix spanning from Asn9 to Ile15 and a poorly defined NH2 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 α-helix, present in the proximal part of i3, may be modulated by the distal part of the loop itself through the Pro233 residue. A molecular model where this possibility is considered as a mechanism for G-protein selection and coupling is presented.
AB - The structural bases that render the third intracellular loop (i3) of the rat angiotensin II AT(1A) 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 α-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 Lys6-Pro7 peptide bond generates two exchanging isomers adopting similar conformations, with an α-helix spanning from Asn9 to Ile15 and a poorly defined NH2 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 α-helix, present in the proximal part of i3, may be modulated by the distal part of the loop itself through the Pro233 residue. A molecular model where this possibility is considered as a mechanism for G-protein selection and coupling is presented.
UR - http://www.scopus.com/inward/record.url?scp=0032946096&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032946096&partnerID=8YFLogxK
U2 - 10.1074/jbc.274.1.227
DO - 10.1074/jbc.274.1.227
M3 - Article
C2 - 9867834
AN - SCOPUS:0032946096
VL - 274
SP - 227
EP - 235
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 1
ER -