Comparison of (/sup 125/I)beta-endorphin binding to rat brain and NG108-15 cells using a monoclonal antibody directed against the opioid receptor

Journal Article · Mon Feb 01 00:00:00 EST 1988 · Mol. Pharmacol.; (United States)

OSTI ID:5357886

Bidlack, J M; O'Malley, W E; Schulz, R

The properties of (/sup 125/I)beta h-endorphin-binding sites from rat brain membranes and membranes from the NG108-15 cell line were compared using a monoclonal antibody directed against the opioid receptor and opioid peptides as probes. The binding of (/sup 125/I)beta h-endorphin to both rat brain and NG108-15 membranes yielded linear Scatchard plots with Kd values of 1.2 nM and 1.5 nM, respectively, and Bmax values of 865 fmol/mg rat brain membrane protein and 1077 fmol/mg NG108-15 membrane protein. A monoclonal antibody, OR-689.2.4, capable of inhibiting mu and delta binding but not kappa binding to rat brain membranes, noncompetitively inhibited the binding of 1 nM (/sup 125/I)beta h-endorphin to rat brain and NG108-15 membranes with an IC50 value of 405 nM for rat brain membranes and 543 nM for NG108-15 membranes. The monoclonal antibody also inhibited the binding of 3 nM (/sup 3/H) (D-penicillamine2, D-penicillamine5) enkephalin to NG108-15 membranes with an IC50 value of 370 nM. In addition to blocking the binding of (/sup 125/I)beta h-endorphin to brain membranes, the antibody also displaced (/sup 125/I)beta h-endorphin from membranes. Site-specific opioid peptides had large variations in their IC50 values depending on whether they were inhibiting (/sup 125/I)beta h-endorphin binding to rat brain or the NG108-15 membranes. When the peptides were tested with the monoclonal antibody for their combined ability to inhibit (/sup 125/I)beta h-endorphin binding to both membrane preparations, the peptides and antibody blocked binding as though they were acting at allosterically coupled sites, not two totally independent sites. These studies suggest that mu-, delta-, and beta-endorphin-binding sites share some sequence homology with the 35,000-dalton protein that the antibody is directed against.

• Research Organization: Univ. of Rochester, NY (USA)
• OSTI ID: 5357886
• Journal Information: Mol. Pharmacol.; (United States), Vol. 33:2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ENDORPHINS
BIOCHEMICAL REACTION KINETICS
RECEPTORS
BRAIN
CELL MEMBRANES
COMPARATIVE EVALUATIONS
IN VITRO
IODINE 125
MOLECULAR WEIGHT
MONOCLONAL ANTIBODIES
RATS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMALS
ANTIBODIES
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM
DAYS LIVING RADIOISOTOPES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
NERVOUS SYSTEM
NEUROREGULATORS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques