Reconstitution of high-affinity opioid agonist binding in brain membranes

Journal Article · Fri Mar 15 00:00:00 EST 1991 · Proceedings of the National Academy of Sciences of the United States of America; (United States)

DOI:https://doi.org/10.1073/pnas.88.6.2171· OSTI ID:5030365

Remmers, A E; Medzihradsky, F ^[1]

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1. Univ. of Michigan Medical School, Ann Arbor (United States)

In synaptosomal membranes from rat brain cortex, the {mu} selective agonist ({sup 3}H)dihydromorphine in the absence of sodium, and the nonselective antagonist ({sup 3}H)naltrexone in the presence of sodium, bound to two populations of opioid receptor sites with K{sub d} values of 0.69 and 8.7 nM for dihydromorphine, and 0.34 and 5.5 nM for naltrexone. The addition of 5 {mu}M guanosine 5{prime}-({gamma}-thio)triphosphate (GTP({gamma}S)) strongly reduced high-affinity agonist but not antagonist binding. Exposure of the membranes to high pH reduced the number of GTP({gamma}-{sup 35}S) binding sites by 90% and low K{sub m}, opioid-sensitive GTPase activity by 95%. In these membranes, high-affinity agonist binding was abolished and modulation of residual binding by GTP({gamma}S) was diminished. Alkali treatment of the glioma cell membranes prior to fusion inhibited most of the low K{sub m} GTPase activity and prevented the reconstitution of agonist binding. The results show that high-affinity opioid agonist binding reflects the ligand-occupied receptor - guanine nucleotide binding protein complex.

• OSTI ID: 5030365
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (United States), Vol. 88:6; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ALKALOIDS
RADIORECEPTOR ASSAY
GTP-ASES
ENZYME ACTIVITY
RECEPTORS
BIOCHEMICAL REACTION KINETICS
BRAIN
CELL MEMBRANES
GLIOMAS
MORPHINE
RATS
SULFUR 35
TRITIUM COMPOUNDS
ACID ANHYDRASES
ANALGESICS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM
CENTRAL NERVOUS SYSTEM DEPRESSANTS
DAYS LIVING RADIOISOTOPES
DISEASES
DRUGS
ENZYMES
EVEN-ODD NUCLEI
HYDROGEN COMPOUNDS
HYDROLASES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
NARCOTICS
NEOPLASMS
NERVOUS SYSTEM
NUCLEI
OPIUM
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
SULFUR ISOTOPES
TRACER TECHNIQUES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques