Current inactivation involves a histidine residue in the pore of the rat lymphocyte potassium channel RGK5

A. E. Busch, R. S. Hurst, R. A. North, J. P. Adelman, M. P. Kavanaugh

Research output: Contribution to journalArticle

46 Scopus citations

Abstract

RGK5 is a rat genomic DNA clone that encodes the n-type potassium channel found in T-lymphocytes and other cells. Current through this channel declines (inactivates) over a period of hundreds of milliseconds during a maintained depolarizing pulse, whether in lymphocytes or when expressed in Xenopus oocytes. Here we demonstrate that an amino acid residue near the outer pore of the channel, histidine401, is involved in the inactivation process. Replacement of this residue by tyrosine, the amino acid found in the equivalent position of the homologous but non-inactivating channel RBK1, reduced inactivation of RGK5 over a 5 s depolarizing pulse from 84.3 ± 1.9% to 18.3 ± 1.1%. Conversely, replacement of this tyrosine in RBK1 (Tyr379) by histidine increased its inactivation from 21.6 ± 1.1% to 42.3 ± 1.5%. These results suggest a mechanism of channel inactivation distinct from that previously described for the A-type potassium channel.

Original languageEnglish (US)
Pages (from-to)1384-1390
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume179
Issue number3
DOIs
StatePublished - Sep 30 1991

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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