Monoclonal antibodies detect the conservation of muscarinic cholinergic receptor structure from Drosophila to human brain and detect possible structural homology with alpha 1-adrenergic receptors.

Abstract

Muscarinic cholinergic receptors isolated from Drosophila heads, rat and human brain, dog heart, and monkey ciliary muscle were examined for structural similarities/differences by utilizing isoelectric focusing, sodium dodecyl sulfate/polyacrylamide gel electrophoresis, and monoclonal antibody crossreactivity. Muscarinic The muscarinic cholinergic receptor mediates various central nervous system activities as well as the function of the parasympathetic side of the autonomic nervous system, including heart rate attenuation and smooth muscle contraction in the eye, intestine, and airways. This laboratory has investigated the structure of the muscarinic cholinergic receptor and found it to be a monomeric protein with a molecular mass of 80,000 daltons (1). Topology studies indicate that the muscarinic receptor is similar to the nicotinic receptor (2) in that over 50% of the receptor protrudes into the extracellular aqueous space and 14% of the receptor is on the cytoplasmic side of the membrane (1).In contrast to the adrenergic receptor system, major differences do not appear to exist in the structure of muscarinic cholinergic receptors isolated from vertebrate heart, brain, and smooth muscle (1). It appears as though the muscarinic receptor may be highly conserved, perhaps throughout a large part of the evolutionary process. There is evidence to suggest that atropine-sensitive acetylcholine responses, indicative of the presence of muscarinic receptors, exist throughout much of the phylogenetic tree, in molluscs, annelids, and arthropods (3, 4), including insects, in which muscarinic receptor-specific radioligand binding has been reported (5-7). a1-Adrenergic receptor monomers are proteins with a molecular mass of 80,000-85,000 daltons (8-10) with a membrane topology and tryptic digest map similar to those of muscarinic receptors (9,10). In the present study we describe the production of monoclonal antibodies specific for muscarinic cholinergic and a1-adrenergic receptors and their use in detecting structural similarities between muscarinic cholinergic receptors isolated from a wide variety of tissues and between muscarinic receptors and rat liver a1-adrenergic receptors. were from New England Nuclear. Other materials were as described (1,(8)(9)(10)(11). MATERIALSTissues and Membranes. Rat and human brain membranes were prepared as described (1). Wild-type Drosophila melanogaster heads were separated from bodies as described (12) and stored at -80°C prior to use. Heads were homogenized in homogenization buffer, consisting of 5 mM sodium phosphate at pH 7.3, 1% sucrose, 10 mM

The binding of pirenzepine to digitonin‐solubilized muscarinic acetylcholine receptors from the rat myocardium

“…solubilized mAChRs from those two tissues persists (Berrie et al, 1985b), but in general the findings support the idea that there is little to distinguish the binding domains of the isolated receptors from cortex and myocardium (Laduron et al, 1981;Venter et al, 1984;Schreiber & Sokolovsky, 1985). Nonetheless, it would probably be premature to dismiss the notion of muscarinic receptor isotypes on this basis since (1) Pz high and low affinity binding sites survive solubilization from the cortex (Berrie et al, 1985c), whereas high affinity sites actually appear after solubilization of the heart, and (2) the affinity of Pz for mAChRs from the rat lacrimal gland is lowered after solubilization (M. Keen et al, unpublished observations), thereby enhancing the selectivity of the drug in this case.…”

Trace amine‐associated receptors and their ligands

“…(2005a, 2005b) also made a surprising observation; contrary to expectations, invertebrate genomes do not contain sequences belonging to the TAAR family of GPCRs in spite of the fact that trace amine binding has been demonstrated in several invertebrate species including Drosophila melanogaster (Saudou et al ., 1990), honeybee ( Apis mellifera ) (Blenau et al ., 2000; Grohmann et al ., 2003) and molluscs (Gerhardt et al ., 1997). This is in contrast to the extensive inter‐species homology reported for adrenoceptors and for muscarinic cholinergic receptors (Venter et al ., 1984; Pelacios et al ., 1989).…”

Variation of cholinergic biomarkers in brain regions and blood components of captive mink

“…ACh, an archaic signaling molecule, has been found in prokaryotes, plants, and mammals (Wessler et al 1999), and the gene sequence or protein structures for ChAT, mACh receptor, and AChE are highly similar among Drosophila, rats, and humans (Venter et al 1984;Oda 1999;Wessler et al 1999). This strong degree of conservation is not surprising because the pathway is integral in basic cellular functions, including cytoskeletal and membrane organization, calcium regulation, mitogenesis, and cell differentiation and migration.…”