151. Ligand Binding Kinetics of Substance P and Neurokinin A Receptors Stably Expressed in Chinese Hamster Ovary Cells and Evidence for Differential Stimulation of Inositol 1,4,5-Trisphosphate and Cyclic AMP Second Messenger Responses
- Author
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Paul Blount, Andrew D. Hershey, Yasuo Takeda, Rita Raddatz, Bruce S. Sachais, and James E. Krause
- Subjects
medicine.medical_specialty ,Molecular Sequence Data ,Substance P ,CHO Cells ,Inositol 1,4,5-Trisphosphate ,Biology ,Ligands ,Second Messenger Systems ,Biochemistry ,Substance-P Receptor ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,Cricetinae ,Internal medicine ,Cyclic AMP ,medicine ,Animals ,Inositol phosphate ,Receptor ,chemistry.chemical_classification ,Base Sequence ,Chinese hamster ovary cell ,Receptors, Neurokinin-2 ,Receptors, Neurokinin-1 ,Molecular biology ,Receptors, Neurotransmitter ,Kinetics ,Endocrinology ,chemistry ,Second messenger system ,Neurokinin A ,Signal transduction - Abstract
Stably transfected Chinese hamster ovary cells expressing either the substance P receptor or neurokinin A receptor were constructed, isolated, and characterized. Equilibrium ligand binding studies performed on whole cells demonstrated that cell lines expressing either of these receptors contained a single class of high-affinity binding sites with an apparent KD of 0.16 nM for the substance P receptor and an apparent KD of 2.1 nM for the neurokinin A receptor. The higher affinity of substance P for its receptor was accounted for by both a greater association rate constant and a lesser dissociation rate constant. The time course and extent of ligand-stimulated inositol 1,4,5-trisphosphate mass increases in both cell lines were similar and displayed rapid and transient kinetics. Ligand-stimulated cyclic AMP accumulation was also apparent in the cell lines, although the time course and magnitude of the responses were substantially different, with the neurokinin A receptor mediating a greater and more prolonged response. These studies establish the presence of functional substance P receptors and neurokinin A receptors in the stably transfected cell lines and provide evidence for agonist-dependent differential stimulation of second messenger responses.
- Published
- 1992
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