Search results for "acetylcholine receptor"
showing 10 items of 263 documents
Expression of Muscarinic Receptor Types in the Primate Ovary and Evidence for Nonneuronal Acetylcholine Synthesis1
2001
The presence of muscarinic receptors (MR) in the ovary of different species has been recognized, but the identity of these receptors as well as ovarian sources of their natural ligand, acetylcholine (ACh), have not been determined. Because luteinized human granulosa cells (GC) in culture express functional MR, we have determined whether the group of the related MR subtypes, M1R, M3R, and M5R, are present in vivo in human and rhesus monkey ovaries. To this end, ribonucleic acids (RNAs) of different human and monkey ovaries as well as RNAs from human GC and monkey oocytes were reverse transcribed and subjected to PCR amplification, followed by sequencing of the amplified complementary DNAs. R…
A Structural Model of the Human α7 Nicotinic Receptor in an Open Conformation
2015
International audience; Nicotinic acetylcholine receptors (nAchRs) are ligand-gated ion channels that regulate chemical transmission at the neuromuscular junction. Structural information is available at low resolution from open and closed forms of an eukaryotic receptor, and at high resolution from other members of the same structural family, two prokaryotic orthologs and an eukary- otic GluCl channel. Structures of human channels however are still lacking. Homology modeling and Molecular Dynamics simulations are valuable tools to predict structures of unknown proteins, however, for the case of human nAchRs, they have been unsuccessful in providing a stable open structure so far. This is du…
The Molecular Anatomy of Human Hsp60 and its Similarity with that of Bacterial Orthologs and Acetylcholine Receptor Reveal a Potential Pathogenetic R…
2012
Heat-shock protein 60 (Hsp60) is ubiquitous and highly conserved being present in eukaryotes and prokaryotes, including pathogens. This chaperonin, although typically a mitochondrial protein, can also be found in other intracellular sites, extracellularly, and in circulation. Thus, it can signal the immune system and participate in the development of inflammation and immune reactions. Both phenomena can be elicited by human and foreign Hsp60 (e.g., bacterial GroEL), when released into the blood by infectious agents. Consequently, all these Hsp60 proteins become part of a complex autoimmune response characterized by multiple cross reactions because of their structural similarities. In this s…
Mapping of a binding site for ATP within the extracellular region of the Torpedo nicotinic acetylcholine receptor beta-subunit.
1997
Using 2,8,5'-[H-3]ATP as a direct photoaffinity label for membrane-bound nicotinic acetylcholine receptor (nAChR) from Torpedo marmorata, we have identified a binding site for ATP in the extracellular region of the beta-subunit of the receptor. Photolabeling was completely inhibited in the presence of saturating concentrations of nonradioactive ATP, whereas neither the purinoreceptor antagonists suramin, theophyllin, and caffeine nor the nAChR antagonists alpha-bungarotoxin and d-tubocurarine affected the labeling reaction. Competitive and noncompetitive nicotinic agonists and Ca2+ increased the yield of the photoreaction by up to 50%, suggesting that the respective binding sites are allost…
Muscarinic modulation of acetylcholine release: Receptor subtypes and possible mechanisms
1989
The release of acetylcholine from central and peripheral neurones can be inhibited and facilitated by muscarine autoreceptors, i.e. receptors located on the cholinergic neurone. In the last few years evidence has accumulated that muscarine receptors are heterogeneous. This chapter describes attempts that have been made to classify the muscarine autoreceptors. In addition, some possible mechanisms behind the neuronal muscarine receptors are examined.
Severe congenital myasthenic syndrome due to homozygosity of the 1293insG ε-acetylcholine receptor subunit mutation
2000
Recently, a congenital myasthenic syndrome (CMS) with end-plate acetylcholine receptor (AChR) deficiency due to missense mutations in the genes for the AChR subunit was described. The first observed patient with this CMS was heteroallelic for the two epsilon-AChR subunit mutations epsilon1101insT and epsilon1293insG. This patient had only a moderate phenotype with mild muscle weakness and abnormal fatigue. We have now found homozygosity for the epsilon1293insG mutation in a severely affected CMS patient, who lost the ability to walk in midchildhood and shows profound weakness and muscle wasting. Our observation allows a genotype-phenotype correlation illustrating how differences in the AChR…
Neuronal Nicotinic Receptors in the Locust Locusta migratoria
1998
We have identified five cDNA clones that encode nicotinic acetylcholine receptor (nAChR) subunits expressed in the nervous system of the locust Locusta migratoria. Four of the subunits are ligand-binding α subunits, and the other is a structural β subunit. The existence of at least one more nAChR gene, probably encoding a β subunit, is indicated. Based on Northern analysis and in situ hybridization, the five subunit genes are expressed. locα1, locα3, andlocβ1 are the most abundant subunits and are expressed in similar areas of the head ganglia and retina of the adult locust. Because Locα3 binds α-bungarotoxin with high affinity, it may form a homomeric nAChR subtype such as the mammalian α7…
High pancuronium sensitivity of axonal nicotinic-acetylcholine receptors in humans during organophosphate intoxication.
1991
The effect of low-dose pancuronium on neuromuscular transmission was studied in 2 patients during the early and late stages of severe organophosphate intoxication. Single evoked compound muscle action potentials (CMAP) were followed by repetitive discharges and a decrement-increment (D-I) phenomenon with 10-, 20-, and 50-Hz supramaximal nerve stimulation. Intravenous pancuronium, 1 mg, abolished the D-I phenomenon, while the repetitive discharges of the CMAP were only partially reduced. It is postulated, that the disappearance of the D-I phenomenon with persistence of the CMAP repetitive discharges results from blockade of nicotinic-acetylcholine receptors located on the terminal axon respo…
Corrigendum to “Hsp60 and AChR cross-reactivity in myasthenia gravis: An update.” [J. Neurol. Sci. 292 (2010) 117–118]
2012
Corrigendum to “Hsp60 and AChR cross-reactivity in myasthenia gravis: An update.” [J. Neurol. Sci. 292 (2010) 117–118] Francesco Cappello ⁎, Antonella Marino Gammazza, Leila Zummo, Everly Conway de Macario, Alberto J.L. Macario a Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Via del Vespro 129, 90127, Palermo, Italy b University of Maryland, IMET, 701 East Pratt Street, 21202, Baltimore, MD, USA
Functional nicotinic acetylcholine receptors on subplate neurons in neonatal rat somatosensory cortex.
2004
The establishment of cortical synaptic circuits during early development requires the presence of subplate neurons (SPn's), a heterogeneous population of neurons capable to integrate and process synaptic information from the thalamus, cortical plate, and neighboring SPn's. An accumulation of cholinergic afferents and nicotinic acetylcholine receptors (nAChRs) has been documentated in the subplate around birth. To assess the developmental role of the cholinergic innervation onto SPn's, we used whole cell patch-clamp recordings of visually identified and biocytin-labeled SPn's in neonatal rat somatosensory cortex. Functional nAChRs were present in 92% of the investigated SPn's. Activation of…