RT Journal Article
SR Electronic
T1 Neurotensin Binding to Extraneural and Neural Receptors: Comparison with Biological Activity and Structure—Activity Relationships
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 11
OP 19
VO 18
IS 1
A1 PATRICK KITABGI
A1 CLAUDINE POUSTIS
A1 CLAUDE GRANIER
A1 JURPHAAS VAN RIETSCHOTEN
A1 JEAN RIVIER
A1 JEAN-LOUIS MORGAT
A1 PIERRE FREYCHET
YR 1980
UL http://molpharm.aspetjournals.org/content/18/1/11.abstract
AB The binding of [3H]neurotensin to a cell line (HT 29) derived from a human colon carcinoma was characterized and compared with [3H]neurotensin binding to rat brain synaptic membranes. Both systems were used as radioreceptor assays for neurotensin and 18 neurotensin synthetic analogs, and the binding affinities thus derived were compared to the biological potencies obtained from the peptide abilities to contract isolated longitudinal smooth muscle strips of the guinea pig ileum. Tritiated neurotensin bound specifically and reversibly to HT 29 cells. The characteristics of [3H]neurotensin binding to cells at 24°C were those of a simple, bimolecular reaction involving one class of noncooperative binding sites. A Kd value of 1.5 nM was independently obtained from association kinetic and equilibrium experiments; total binding capacity was 37 fmol/106 cells (22,000 neurotensin-binding sites/cell). Peptides structurally not related to neurotensin did not affect [3H]neurotensin binding. These binding characteristics were very similar to those observed for the binding of [3H]neurotensin to rat brain synaptic membranes. When the binding affinities of neurotensin and neurotensin analogs were compared in the extraneural (HT 29 cells) and neural (brain membranes) systems, a highly significant correlation between the two binding systems was observed. A highly significant correlation was also found when the biological potencies of neurotensin and neurotensin analogs were compared with their binding affinities in either the neural or the extraneural radioreceptor assay. The positive charge on both arginyl residues 8 and 9 and the L-configuration of Arg9 were important for binding and biological activity. An aromatic residue in the L-configuration was required in position 11 of the neurotensin molecule. The side-chain methyl groups of Ile12 and carboxy-terminal residue Leu13, as well as the presence of Leu13 in the L-configuration, were required for activity. ACKNOWLEDGMENTS We would like to thank Dr. A. Zweibaum for kindly supplying us with HT 29 cells. We also wish to thank G. Visciano for expert technical assistance and J. Duch for excellent secretarial assistance.