High impact information on nAcRbeta-64B

• In situ hybridization with an intron-specific probe indicated codistribution of immature and mature ard RNAs in pupae and adult flies [1].
• Neuronal acetylcholine receptors in Drosophila: mature and immature transcripts of the ard gene in the developing central nervous system [1].
• In situ hybridization experiments revealed ard gene expression in nervous tissue only [1].
• In adult muscle, transcription of the nicotinic acetylcholine receptor (AChR) is restricted to the nuclei located at the neuromuscular junction [2].
• These findings establish the expected connection with a presynaptic trophic factor whose release contributes to the accumulation of AChR subunit mRNAs at the motor endplate [2].

Biological context of nAcRbeta-64B

• The deduced amino acid sequence of SBD displays remarkable similarity to the Drosophila alpha-subunits, ALS and SAD, while homology to the Drosophila beta-subunit ARD is less pronounced [3].
• During metamorphosis, a temporal relationship between the morphogenesis of the optic lobe and expression of AChR64B transcripts was observed [4].
• The Drosophila genomic clone hybridized to salivary gland polytene chromosome 3L within region 64B and was termed AChR64B [4].
• The ard gene thus contains less introns than vertebrate muscle AChR genes, but, with one exception, the positions of the resident introns are precisely conserved [5].
• To investigate the mechanism of neonicotinoid selectivity, we have examined the effects of mutations to basic amino acid residues in loop D of the nAChR acetylcholine (ACh) binding site on the interactions with imidacloprid [6].

Anatomical context of nAcRbeta-64B

• Immunohistochemical studies revealed that Dalpha3 is co-distributed with the beta-subunit ARD in synaptic neuropil regions of the optic lobe [7].
• AChR64B transcripts were localized to the cellular regions of the central nervous system during embryonic, larval, pupal, and adult stages of development [4].
• Three cDNAs (ALS, D alpha 2 and ARD) isolated from the nervous system of Drosophila and encoding putative nicotinic acetylcholine receptor subunits were expressed in Xenopus oocytes in order to study their functional properties [8].
• Both ALS and ARD antisera removed 20-30% of the high-affinity binding sites for the nicotinic antagonist 125I-alpha-bungarotoxin (125I-alpha-Btx) from detergent extracts of fly head membranes [9].
• Using the Drosophila melanogaster S2 cell line, stably expressing a cloned muscarinic acetylcholine receptor (AChR), DM1, we have applied gene silencing by double-stranded RNA interference (RNAi) to knock down gene products involved in DM1-mediated calcium signalling [10].

Associations of nAcRbeta-64B with chemical compounds

• Neuronal nicotinic acetylcholine receptors of Drosophila melanogaster: the alpha-subunit dalpha3 and the beta-type subunit ARD co-assemble within the same receptor complex [7].
• The coplanar system between the electronegative tip and guanidine-amidine moiety extends the conjugation and facilitates negative charge (delta(-)) flow toward the tip, thereby enhancing interaction with the proposed cationic subsite such as lysine or arginine in the Drosophila nAChR [11].
• Likewise, T77K;E79R and T77N;E79R double mutations in the Dalpha2beta2 nAChR also resulted in a shift to a higher affinity for imidacloprid, which exceeded that observed for a single mutation of Thr77 to basic residues [6].
• There is a large group of divergent C. elegans nAChR-like subunits partially resolved into clades but no orthologues of 5HT3-type serotonin receptors in the invertebrates [12].
• Crosshybridization with a Torpedo nAChR cDNA probe allowed isolation of a cholinergic receptor cDNA (ARD) from the Drosophila CNS [13].

Analytical, diagnostic and therapeutic context of nAcRbeta-64B

• Here we report the molecular cloning, heterologous expression and characterization of this putative Drosophila nAChR subunit (Dbeta3) [14].
• This observation is consistent with previous immunoprecipitation data indicating that the ALS and ARD proteins are integral components of the same hetero-oligomeric receptor that binds the nicotinic antagonist alpha-bungarotoxin with high affinity [15].
• The genes coding for the beta and epsilon subunits of the mouse muscle nicotinic acetylcholine receptor (nAChR) were mapped by Southern blot analysis, and the entire loci for both genes cloned [16].
• Sequence analysis has identified an open reading frame of 509 amino acids with features typical of nAChR subunits [17].
• The insect nAChR is the primary target site for the neonicotinoid insecticides, thereby providing an incentive to explore its functional architecture with neonicotinoid radioligands, photoaffinity probes and affinity chromatography matrices [18].

References