Specific binding of (/sup 3/H-Tyr8)physalaemin to rat submaxillary gland substance P receptor

Journal Article · Mon Dec 31 23:00:00 EST 1984 · Mol. Pharmacol.; (United States)

OSTI ID:5558524

Bahouth, S W; Lazaro, D M; Brundish, D E; Musacchio, J M

(/sup 3/H)Physalaemin ((/sup 3/H)PHY) binds to a single class of noninteracting sites on rat submaxillary gland membranes suspended in high ionic strength media with a KD of 2.7 nM, a Bmax of 240 fmol/mg of protein, and low nonspecific binding. The relative potencies of substance P (SP) and its fragments in competing with (/sup 3/H)PHY correlate with their relative salivation potencies. This indicates that (/sup 3/H)PHY interacts with a physiologically relevant SP receptor. In low ionic strength media, the KD of (/sup 3/H)PHY does not change, but SP and some of its fragments are more potent than PHY in competing with (/sup 3/H) PHY. Computer-assisted analysis of (/sup 3/H)PHY and (/sup 3/H)SP binding in high and low ionic strength media demonstrated that both peptides are equipotent in high ionic strength but that the affinity of SP increases by 70-fold in low ionic strength. The SP fragments that contain a basic residue in positions 1 and/or 3 also display an increased affinity in low ionic strength. These findings document that (/sup 3/H)PHY binding in high ionic strength (mu . 0.6) accurately reflects the pharmacological potencies of agonists on the SP-P receptor. The binding of (/sup 3/H)PHY, like that of (/sup 3/H)SP, increases by the addition of divalent cations (Mg2+ greater than Ca2+ greater than Mn2+). Guanine nucleotides decrease (/sup 3/H)PHY binding by decreasing the Bmax to the same level (160 fmol/mg of protein), in the presence or absence of Mg2+.

• Research Organization: New York Univ. Medical Center, NY
• OSTI ID: 5558524
• Journal Information: Mol. Pharmacol.; (United States), Journal Name: Mol. Pharmacol.; (United States) Vol. 27:1; ISSN MOPMA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AFFINITY
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BODY
CHEMICAL ANALYSIS
CHEMICAL BONDS
CHEMISTRY
COMPUTERS
CPB
GLANDS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
ORGANIC COMPOUNDS
ORGANS
PEPTIDES
PROTEINS
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SALIVARY GLANDS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES