Truncated K+ channel DNA sequences specifically suppress lymphocyte K+ channel gene expression.
We have constructed a series of deletion mutants of Kv1.3, a Shaker-like, voltage-gated K+ channel, and examined the ability of these truncated mutants to form channels and to specifically suppress full-length Kv1.3 currents. These constructs were expressed heterologously in both Xenopus oocytes and a mouse cytotoxic T cell line. Our results show that a truncated mutant Kv1.3 must contain both the amino terminus and the first transmembrane-spanning segment, S1, to suppress full-length Kv1.3 currents. Amino-terminal-truncated DNA sequences from one subfamily suppress K+ channel expression of members of only the same subfamily. The first 141 amino acids of the amino-terminal of Kv1.3 are not necessary for channel formation. Deletion of these amino acids yields a current identical to that of full-length Kv1.3, except that it cannot be suppressed by a truncated Kv1.3 containing the amino terminus and S1. To test the ability of truncated Kv1.3 to suppress endogenous K+ currents, we constructed a plasmid that contained both truncated Kv1.3 and a selection marker gene (mouse CD4). Although constitutively expressed K+ currents in Jurkat (a human T cell leukemia line) and GH3 (an anterior pituitary cell line) cells cannot be suppressed by this double-gene plasmid, stimulated (up-regulated) Shaker-like K+ currents in GH3 cells can be suppressed.
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Department of Physiology, University of Pennsylvania, Philadelphia 19104-6085.
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D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D002460:Cell Line; D004247:DNA / Q000235:genetics*; D004594:Electrophysiology; D005260:Female; D015870:Gene Expression; D006801:Humans; D066298:In Vitro Techniques; D051664:Kv1.3 Potassium Channel; D008214:Lymphocytes / Q000378:metabolism*; D051379:Mice; D009865:Oocytes / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated; D018075:RNA, Complementary / Q000235:genetics; D017384:Sequence Deletion; D013489:Suppression, Genetic; D014162:Transfection; D014982:Xenopus laevis
C496973:KCNA3 protein, human; C496974:Kcna3 protein, mouse; D051664:Kv1.3 Potassium Channel; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D018075:RNA, Complementary; D004247:DNA