Cloning and expression of the human kv4.3 potassium channel.
We report on the cloning and expression of hKv4.3, a fast inactivating, transient, A-type potassium channel found in both heart and brain that is 91% homologous to the rat Kv4.3 channel. Two isoforms of hKv4.3 were cloned. One is full length (hKv4.3 long), and the other has a 19 amino acid deletion (hKv4.3 short). RT-PCR shows that the brain contains both forms of the channel RNA, whereas the heart predominantly has the longer version. Both versions of the channel were expressed in Xenopus oocytes, and both contain a significant window or noninactivating current seen near potentials of -30 to -40 mV. The inactivation curve for hKv4.3 short is shifted 10 mV positive relative to hKv4.3 long. This causes the peak window current for the short version to occur near -30 mV and the peak for the longer version to be at -40 mV. There was little difference in the recovery from inactivation or in the kinetics of inactivation between the two isoforms of the channel.
Dilks
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CNS Research, Wyeth-Ayerst Research, Princeton, New Jersey 08543, USA.
Ling
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HP
Cockett
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Sokol
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Numann
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D000818:Animals; D001923:Brain Chemistry / Q000502:physiology; D003001:Cloning, Molecular; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D007700:Kinetics; D008564:Membrane Potentials / Q000502:physiology; D008969:Molecular Sequence Data; D018485:Muscle Fibers, Skeletal / Q000737:chemistry*; D009206:Myocardium / Q000737:chemistry / Q000166:cytology; D009474:Neurons / Q000737:chemistry*; D009865:Oocytes / Q000502:physiology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D051672:Shal Potassium Channels; D014981:Xenopus
C497021:KCND3 protein, human; C497023:Kcnd3 protein, rat; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D051672:Shal Potassium Channels