Human α3β4 neuronal nicotinic receptors show different stoichiometry if they are expressed in Xenopus oocytes or mammalian HEK293 cells
| Autor: | Steven D. Broadbent, Giovanna Hofmann, Paraskevi Krashia, Mirko Moroni, Sebastian Kracun, Paul J. Groot-Kormelink, Lucia G. Sivilotti, Marco Beato |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: |
Patch-Clamp Techniques
Dimethylphenylpiperazinium Xenopus Alpha (ethology) lcsh:Medicine Receptors Nicotinic Cell Line 03 medical and health sciences 0302 clinical medicine medicine Animals Humans Beta (finance) Receptor lcsh:Science 030304 developmental biology G alpha subunit Pharmacology 0303 health sciences Multidisciplinary biology Physiology/Neuronal Signaling Mechanisms lcsh:R Cell biology Transmembrane domain Biochemistry biology.protein Physiology/Cell Signaling Oocytes lcsh:Q 030217 neurology & neurosurgery ATP synthase alpha/beta subunits Cys-loop receptors medicine.drug Research Article |
| Zdroj: | PLoS ONE, Vol 5, Iss 10, p e13611 (2010) PLoS ONE |
| ISSN: | 1932-6203 |
| Popis: | Background: The neuronal nicotinic receptors that mediate excitatory transmission in autonomic ganglia are thought to be formed mainly by the alpha 3 and beta 4 subunits. Expressing this composition in oocytes fails to reproduce the properties of ganglionic receptors, which may also incorporate the alpha 5 and/or beta 2 subunits. We compared the properties of human alpha 3 beta 4 neuronal nicotinic receptors expressed in Human embryonic kidney cells (HEK293) and in Xenopus oocytes, to examine the effect of the expression system and alpha:beta subunit ratio.Methodology/Principal Findings: Two distinct channel forms were observed: these are likely to correspond to different stoichiometries of the receptor, with two or three copies of the alpha subunit, as reported for alpha 4 beta 2 channels. This interpretation is supported by the pattern of change in acetylcholine (ACh) sensitivity observed when a hydrophilic Leu to Thr mutation was inserted in position 9' of the second transmembrane domain, as the effect of mutating the more abundant subunit is greater. Unlike alpha 4 beta 2 channels, for alpha 3 beta 4 receptors the putative two-alpha form is the predominant one in oocytes (at 1:1 alpha:beta cRNA ratio). This two-alpha form has a slightly higher ACh sensitivity (about 3-fold in oocytes), and displays potentiation by zinc. The putative three-alpha form is the predominant one in HEK cells transfected with a 1:1 alpha:beta DNA ratio or in oocytes at 9:1 alpha:beta RNA ratio, and is more sensitive to dimethylphenylpiperazinium (DMPP) than to ACh. In outside-out single-channel recordings, the putative two-alpha form opened to distinctive long bursts (100 ms or more) with low conductance (26 pS), whereas the three-alpha form gave rise to short bursts (14 ms) of high conductance (39 pS).Conclusions/Significance: Like other neuronal nicotinic receptors, the alpha 3 beta 4 receptor can exist in two different stoichiometries, depending on whether it is expressed in oocytes or in mammalian cell lines and on the ratio of subunits transfected. |
| Databáze: | OpenAIRE |
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