Certain aspects of alpha 6-containing receptor pharmacology have been studied by using chimeric subunits containing the alpha 6 ligand-binding domain. However, these chimeras would not be sensitive to an alpha 6-selective channel blocker; therefore we developed an alpha 6 chimera (alpha 4/6) that has the transmembrane and intracellular domains of alpha 3 and the extracellular domain of alpha 4. We examined the pharmacological properties of alpha 4/6-containing receptors and other important nAChR subtypes, Selleckchem Avapritinib including alpha 7, alpha 4 beta 2, alpha 4 beta 4, alpha 3 beta 4, alpha 3 beta 2, and alpha 3 beta 2 beta 3, as well as receptors

containing alpha 6/3 and alpha 6/4 chimeras. Our data show that the absence or presence of the beta 4 subunit is an important factor for sensitivity to the ganglionic

blocker mecamylamine, and that dihydro-beta-erythroidine is most effective on subtypes selleckchem containing the alpha 4 subunit extracellular domain. Receptors containing the alpha 6/4 subunit are sensitive to alpha-conotoxin PIA, while receptors containing the reciprocal alpha 4/6 chimera are insensitive. In experiments with novel antagonists of nicotine-evoked dopamine release, the alpha 4/6 chimera indicated that structural rigidity was a key element of compounds that could result in selectivity for noncompetitive inhibition of alpha 6 containing receptors. Our data extend the information available on prototypical nAChR Fazadinium bromide antagonists, and establish the alpha 4/6 chimera as a useful new tool for screening drugs as selective nAChR antagonists. (c) 2008 Elsevier Ltd. All rights reserved.”
“The replication/transcription complex of the arterivirus equine arteritis virus (EAV) is associated with paired membranes and/or double-membrane vesicles (DMVs) that are thought to originate from the endoplasmic reticulum.

Previously, coexpression of two putative transmembrane nonstructural proteins (usp2 and nsp3) was found to suffice to induce these remarkable membrane structures, which are typical of arterivirus infection. Here, site-directed mutagenesis was used to investigate the role of nsp3 in more detail. Liberation of the hydrophobic N terminus of nsp3, which is normally achieved by cleavage of the nsp2/3 junction by the nsp2 protease, was nonessential for the formation of DMVs. However, the substitution of each of a cluster of four conserved cysteine residues, residing in a predicted luminal loop of nsp3, completely blocked DMV formation. Some of these mutant nsp3 proteins were also found to be highly cytotoxic, in particular, exerting a dramatic effect on the endoplasmic reticulum. The functionality of an engineered N glycosylation site in the cysteine-containing loop confirmed both its presence in the lumen and the transmembrane nature of nsp3.