title: Characterization and functional expression of genomic DNA encoding the human lymphocyte type n potassium channel.
abstract: Voltage-gated potassium channels play important functional roles in the development and maintenance of human lymphocyte functions. One such channel, known as the type n channel, has been well defined in human T cells and exhibits unique functional properties that distinguish it from other species of potassium channels. We report the characterization of a human genomic DNA clone, HGK5, encoding a 523-amino-acid potassium channel protein encoded by an open reading frame on a single exon. RNA transcribed in vitro from HGK5 genomic DNA directs expression of functional voltage-dependent potassium currents in Xenopus oocytes. The functional characteristics of the expressed channels are strikingly similar to those of the type n channel on human T lymphocytes. This, together with the presence of significant levels of HGK5 mRNA in human T lymphocytes, supports the notion that HGK5 encodes the human type n voltage-gated potassium channel. The effects of concanavalin A treatment on HGK5 mRNA levels in cultured human T lymphocytes was also examined. Mitogenic concentrations of concanavalin A induced a time-dependent decrease in HGK5 mRNA levels, suggesting that previously observed increases in potassium current density following concanavalin A treatment of human T lymphocytes are not due to increased transcriptional activity of the type n potassium channel gene.
authors.affiliation: Vollum Institute, Oregon Health Sciences University, Portland 97201.
authors.forename: Y C
authors.initials: YC
authors.lastname: Cai
authors.forename: P B
authors.initials: PB
authors.lastname: Osborne
authors.forename: R A
authors.initials: RA
authors.lastname: North
authors.forename: D C
authors.initials: DC
authors.lastname: Dooley
authors.forename: J
authors.initials: J
authors.lastname: Douglass
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004247:DNA; D015342:DNA Probes; D006801:Humans; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism; D015183:Restriction Mapping; D013601:T-Lymphocytes / Q000378:metabolism; D014981:Xenopus
chemical_list: D015342:DNA Probes; D015221:Potassium Channels; D004247:DNA