Identification of the Kv2.1 K+Channel as a Major Component of the Delayed Rectifier K+Current in Rat Hippocampal Neurons

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Abstract
Molecular cloning studies have revealed the existence of a large family of voltage-gated K+channel genes expressed in mammalian brain. This molecular diversity underlies the vast repertoire of neuronal K+channels that regulate action potential conduction and neurotransmitter release and that are essential to the control of neuronal excitability. However, the specific contribution of individual K+channel gene products to these neuronal K+currents is poorly understood. We have shown previously, using an antibody, “KC,” specific for the Kv2.1 K+channel α-subunit, the high-level expression of Kv2.1 protein in hippocampal neuronsin situand in culture. Here we show that KC is a potent blocker of K+currents expressed in cells transfected with the Kv2.1 cDNA, but not of currents expressed in cells transfected with other highly related K+channel α-subunit cDNAs. KC also blocks the majority of the slowly inactivating outward current in cultured hippocampal neurons, although antibodies to two other K+channel α-subunits known to be expressed in these cells did not exhibit blocking effects. In all cases the blocking effects of KC were eliminated by previous incubation with a recombinant fusion protein containing the KC antigenic sequence. Together these studies show that Kv2.1, which is expressed at high levels in most mammalian central neurons, is a major contributor to the delayed rectifier K+current in hippocampal neurons and that the KC antibody is a powerful tool for the elucidation of the role of the Kv2.1 K+channel in regulating neuronal excitability.

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