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pubmed:abstractText |
Voltage-gated K+ channels play an important role in the control of neuronal excitability and synaptic plasticity. Their low abundance and extraordinary heterogeneity have rendered their purification from natural sources difficult. We have previously cloned a voltage-gated K(+)-channel gene, Shaker, from Drosophila. The Shaker K(+)-channel polypeptide resembles one of the four internal repeats of a Na(+)- or Ca(2+)-channel alpha subunit, suggesting that this example of a K+ channel contains four identical or homologous subunits. Similar K(+)-channel polypeptides have been characterized from mammals, other vertebrate and invertebrate species, and from plants. Electrophysiological studies of K+ channels expressed in Xenopus oocytes suggest that they are indeed tetramers, and heteromultimeric K+ channels have been found in the mammalian brain. Until now, however, no K+ channel, nor any other member of the superfamily of voltage-gated ion channels, has been characterized by electron microscopy or other structural analysis.
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