Efficient expression of rat brain type IIA Na+ channel alpha subunits in a somatic cell line. |
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Authors: | J W West T Scheuer L Maechler W A Catterall |
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Institution: | Department of Pharmacology, University of Washington, Seattle 98195. |
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Abstract: | Type IIA rat brain Na+ channel alpha subunits were expressed in CHO cells by nuclear microinjection or by transfection using a vector containing both metallothionein and bacteriophage SP6 promoters. Stable cell lines expressing Na+ channels were isolated, and whole-cell Na+ currents of 0.9-14 nA were recorded. The mean level of whole-cell Na+ current (4.5 nA) corresponds to a cell surface density of approximately 2 channels active at the peak of the Na+ current per microns 2, a density comparable to that observed in the cell bodies of central neurons. The expressed Na+ channels had the voltage dependence, rapid activation and inactivation, and rapid recovery from inactivation characteristic of Na+ channels in brain neurons, bound toxins at neurotoxin receptor sites 1 and 3 with normal properties, and were posttranslationally processed to a normal mature size of 260 kd. Expression of Na+ channel cDNA in CHO cells driven by the metallothionein promoter accurately and efficiently reproduces native Na+ channel properties and provides a method for combined biochemical and physiological analysis of Na+ channel structure and function. |
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