Muscarinic acetylcholine receptor subtypes which selectively couple to phospholipase C: Pharmacological and biochemical properties

Journal Article · Fri Dec 14 00:00:00 EST 1990 · Biochemical and Biophysical Research Communications; (USA)

DOI:https://doi.org/10.1016/S0006-291X(05)80087-7· OSTI ID:6152436

Buck, M A; Fraser, C M ^[1]

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1. National Institute on Alcohol Abuse and Alcoholism, Rockville, MD (USA)

The pharmacological and biochemical properties of rat m1 and m3 muscarinic acetylcholine receptors (mAChR) stably transfected into Chinese hamster ovary-K1 (CHO) cells were characterized with ligand binding, affinity labeling and biochemical assays. Both mAChR subtypes display saturable, high affinity binding of (3H)-quinuclidinyl benzilate (QNB) and a rank order of antagonist potency of QNB greater than atropine greater than pirenzepine greater than AF-DX 116. Carbachol displacement of (3H)-QNB binding to the m3 mAChR revealed an approximate 17-fold higher affinity than observed with the m1 mAChR. (3H)-propylbenzilylcholine mustard (PrBCM) labeling of mAChR revealed that m1 and m3 mAChR migrated on SDS-polyacrylamide gels with apparent molecular masses of 80,000 and 94,000 daltons, respectively, consistent with the known differences in their molecular sizes. Both m1 and m3 mAChR elicited dose-dependent increases in the hydrolysis of phosphoinositides; however, the maximal increase in total inositol phosphates elicited with the m1 mAChR was approximately 2-fold greater than that observed in cells expressing similar densities of m3 mAChR. Agonist activation of the m1 mAChR also elicited increases in basal and forskolin-stimulated cAMP, whereas the m3 mAChR had no effect on intracellular cAMP levels. These data suggest that although m1 and m3 mAChR display a considerable degree of structural homology, they exhibit distinct pharmacological and biochemical properties.

• OSTI ID: 6152436
• Journal Information: Biochemical and Biophysical Research Communications; (USA), Vol. 173:2; ISSN 0006-291X
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ACETYLCHOLINE
RECEPTORS
CHEMICAL PROPERTIES
BIOCHEMICAL REACTION KINETICS
CHO CELLS
DOSE-RESPONSE RELATIONSHIPS
ELECTROPHORESIS
LIPASES
MOLECULAR WEIGHT
RATS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
AMINES
AMMONIUM COMPOUNDS
ANIMAL CELLS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
CARBOXYLESTERASES
DRUGS
ENZYMES
ESTERASES
ESTERS
HYDROGEN COMPOUNDS
HYDROLASES
ISOTOPE APPLICATIONS
KINETICS
MAMMALS
MEMBRANE PROTEINS
NEUROREGULATORS
ORGANIC COMPOUNDS
PARASYMPATHOMIMETICS
PROTEINS
QUATERNARY COMPOUNDS
REACTION KINETICS
RODENTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques