Comparative molecular modeling on 3D-structure of opioid receptor-like 1 receptor
Abstract
"AIM:
To build the three-dimensional structure of opioid receptor-like 1 (ORL1) receptor.
METHODS:
Structural elements of ORL1 receptor were predicted from sequence alignments of opioid and related receptors of G protein-coupled receptor (GPCR) based on (i) the consensus, biophysical interpretations of alignment-derived properties, and (ii) tertiary structural homology to frog rhodopsin; The extracellular loops of ORL1 were built by self-constructed database searching based on geometrical constraints; initial model was refined computationally with energy minimization by molecular mechanics method.
RESULTS:
The calculated structure of ORL1 receptor has clusters of hydrogen bonds existing in interhelices and extracellular loops; the ORL1 receptor has a possible ligand-binding ""crevice"" situated on the extraside of the transmembrane domains between helices 3, 5, 6, and 7, which is partially covered by the extracellular loop 2 (EL-2); The binding cavity may consist of a ""highly conserved region"" involving the residues of Asp130, Tyr131, and an outer ""conservatively variable region"" containing the residues near the interface of transmembrane (TM) helices-EL loops; The molecular model obtained is qualitatively consistent with ligand affinities, hybrid peptide studies, and other experimental data.
CONCLUSION:
The structural model of ORL1 receptor from this study is helpful for clarifying experimental observations of ligands interacting with opioid receptors, and for designing new biological investigations."
Keywords:
To build the three-dimensional structure of opioid receptor-like 1 (ORL1) receptor.
METHODS:
Structural elements of ORL1 receptor were predicted from sequence alignments of opioid and related receptors of G protein-coupled receptor (GPCR) based on (i) the consensus, biophysical interpretations of alignment-derived properties, and (ii) tertiary structural homology to frog rhodopsin; The extracellular loops of ORL1 were built by self-constructed database searching based on geometrical constraints; initial model was refined computationally with energy minimization by molecular mechanics method.
RESULTS:
The calculated structure of ORL1 receptor has clusters of hydrogen bonds existing in interhelices and extracellular loops; the ORL1 receptor has a possible ligand-binding ""crevice"" situated on the extraside of the transmembrane domains between helices 3, 5, 6, and 7, which is partially covered by the extracellular loop 2 (EL-2); The binding cavity may consist of a ""highly conserved region"" involving the residues of Asp130, Tyr131, and an outer ""conservatively variable region"" containing the residues near the interface of transmembrane (TM) helices-EL loops; The molecular model obtained is qualitatively consistent with ligand affinities, hybrid peptide studies, and other experimental data.
CONCLUSION:
The structural model of ORL1 receptor from this study is helpful for clarifying experimental observations of ligands interacting with opioid receptors, and for designing new biological investigations."