Characterization and functional expression of genomic DNA encoding the human lymphocyte type n potassium channel.
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Cai YC, Osborne PB, North RA, Dooley DC, Douglass J
Characterization and functional expression of genomic DNA encoding the human lymphocyte type n potassium channel.
DNA Cell Biol. 1992 Mar;11(2):163-72.
- PubMed ID
- 1547020 [ View in PubMed]
- 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.