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Conformational characterization of a peptide mimetic of the third cytoplasmic loop of the G‐protein coupled parathyroid hormone/parathyroid hormone related protein receptor
Author(s) -
Pellegrini Maria,
Royo Miriam,
Chorev Michael,
Mierke Dale F.
Publication year - 1996
Publication title -
peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/(sici)1097-0282(1996)40:6<653::aid-bip5>3.0.co;2-v
Subject(s) - chemistry , micelle , parathyroid hormone , peptide , crystallography , biophysics , stereochemistry , aqueous solution , biochemistry , calcium , organic chemistry , biology
The third‐cytoplasmic loop of the G‐protein coupled receptor responsible for the activity of parathyroid hormone and parathyroid hormone‐related protein has been structurally characterized in aqueous solution in the presence of sodium dodecylsulfate and dodecylphosphocholine micelles. The high‐resolution conformation of the 29‐amino acid peptide containing the sequence of the cytoplasmic loop was obtained by CD and nmr. The structure was refined using a two‐step distance geometry based method that first includes the removal of all side chains to quickly locate the globular fold of the peptide. After a simulated annealing protocol, the side chains are added in a random fashion. The resulting conformation was further refined with nuclear Overhauser enhancement restrained molecular dynamics using a two‐phase simulation cell consisting of carbon tetrachloride and water as a mimetic of the biphasic, hydrophobic/hydrophilic character of the micelles in which the experimental measurements were carried out. The topological orientation of the cycloplasmic loop within the micelle was determined by addition of 5‐doxylstearate and monitoring the decrease of nmr signal intensities from the radical‐induced relaxation. The conformation and relative orientation of the peptide provided insight into the mechanism by which the cytoplasmic portion of the receptor activates the heterotrimeric, guanine nucleotide‐binding regulatory protein, one of the first steps in signal transduction. © 1997 John Wiley & Sons, Inc. Biopoly 40: 653–666, 1996