GSBS Student Publications

Title

Regulation of substance P receptor affinity by guanine nucleotide-binding proteins

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Physiology

Date

7-1-1989

Document Type

Article

Medical Subject Headings

Alkalies; Animals; GTP-Binding Proteins; Guanosine 5'-O-(3-Thiotriphosphate); Guanosine Triphosphate; Hydrogen-Ion Concentration; Indicators and Reagents; Rats; Receptors, Neurokinin-1; Receptors, Neurotransmitter; Succinimides; Thionucleotides

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

The binding of substance P (SP) to receptors in peripheral tissues as well as in the CNS is subject to regulation by guanine nucleotides. In this report, we provide direct evidence that this effect is mediated by a guanine nucleotide-binding regulatory protein (G-protein) that is required for high-affinity binding of SP to its receptor. Rat submaxillary gland membranes bind a conjugate of SP and 125I-labeled Bolton-Hunter reagent (125I-BHSP) with high affinity (KD = 1.2 +/- 0.4 X 10(-9) M) and sensitivity to guanine nucleotide inhibition. Treatment of the membranes with alkaline buffer (pH 11.5) causes a loss of the high-affinity, GTP-sensitive binding of 125I-BHSP and a parallel loss of [35S]guanosine 5'-(3-O-thio)triphosphate ([35S]GTP gamma S) binding activity. Addition of purified G-proteins from bovine brain to the alkaline-treated membranes restores high-affinity 125I-BHSP binding. Reconstitution is maximal when the G-proteins are incorporated into the alkaline-treated membranes at a 30-fold stoichiometric excess of GTP gamma S binding sites over SP binding sites. Both Go (a pertussis toxin-sensitive G-protein having a 39,000-dalton alpha-subunit) and Gi (the G-protein that mediates inhibition of adenylate cyclase) appear to be equally effective, whereas the isolated alpha-subunit of Go is without effect. The effects of added G-proteins are specifically reversed by guanine nucleotides over the same range of nucleotide concentrations that decreases high-affinity binding of 125I-BHSP to native membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Rights and Permissions

Citation: J Neurochem. 1989 Jul;53(1):264-72.

Related Resources

Link to article in PubMed

Journal Title

Journal of neurochemistry

PubMed ID

2542462