Presynaptic A-current based on heteromultimeric K+ channels detected in vivo.
A wide variety of voltage-gated K+ channels are involved in the regulation of neuronal excitability and synaptic transmission. Their heterogeneity arises in part from the large number of genes encoding different K+ channel subunits (reviewed in ref. 1). In addition, heterologous expression studies indicate that assembly of distinct subunits into heteromultimeric channels may contribute further to K+ channel diversity. A question has been whether heteromeric K+ channels actually form in vivo, and if so, whether specific combinations of subunits could account for major K+ currents identified in neurons. We present here biochemical evidence that Kv1.4 and Kv1.2, two K+ channel subunits of the Shaker subfamily, co-assemble in rat brain. The Kv1.4/Kv1.2 heteromultimer combines features of both parent subunits, resulting in an A-type K+ channel. Immunocytochemical evidence suggests that the heteromultimers are localized in axons and nerve terminals. We propose that Kv1.4/Kv1.2 heteromultimers may form the molecular basis of a presynaptic A-type K+ channel involved in the regulation of neurotransmitter release.
Sheng
M
M
Department of Physiology, Howard Hughes Medical Institute, University of California, San Francisco 94143-0724.
Liao
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D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D002847:Chromatography, Agarose; D004594:Electrophysiology; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000378:metabolism*; D011233:Precipitin Tests; D051381:Rats; D013569:Synapses / Q000378:metabolism*
D008565:Membrane Proteins; D015221:Potassium Channels