Electrically silent potassium channel subunits from human lens epithelium.
We describe the cloning and characterization of the first human members, hKv9.1 and hKv9.3, of the electrically silent delayed-rectifying-like K+ channel subfamily. Their modulatory effects on the electrically active subfamily member hKv2.1 are also quantified. The hKv9 K+ channels were isolated from a human lens epithelium cDNA library, but both hKv9.1 mRNA and hKv9.3 mRNA were found to coexist with the mRNA for hKv2.1 in a large number of human tissues. The hKv9.1 gene is composed of a minimum of five exons, with at least two alternatively spliced exons in the 5'-untranslated region (UTR). In contrast, the hKv9.3 gene is intronless across the coding region, 3'-UTR, and all of the analyzed 5'-UTR. Radiation hybrid mapping localized the hKv9.1 gene to 20q12 and the hKv9.3 gene to 2p24. Each electrically silent subunit, when coexpressed with hKv2.l, slows deactivation and inactivation compared with hKv2. 1 expressed alone. In addition, each results in an increment in the single channel conductance.
Shepard
A R
AR
Departments of Physiology/Biophysics and Ophthalmology, Mayo Foundation, Rochester, Minnesota 55905, USA.
Rae
J L
JL
D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002460:Cell Line; D002874:Chromosome Mapping; D006224:Cricetinae; D051668:Delayed Rectifier Potassium Channels; D004594:Electrophysiology; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D007908:Lens, Crystalline / Q000378:metabolism*; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated; D014018:Tissue Distribution; D014162:Transfection
D051668:Delayed Rectifier Potassium Channels; C503456:KCNS1 protein, human; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated