A ring of eight conserved negatively charged amino acids doubles the conductance of BK channels and prevents inward rectification

Tinatin I. Brelidze, Xiaowei Niu, Karl L. Magleby

Research output: Contribution to journalArticlepeer-review

107 Scopus citations

Abstract

Large-conductance Ca2+-voltage-activated K+ channels (BK channels) control many key physiological processes, such as neurotransmitter release and muscle contraction. A signature feature of BK channels is that they have the largest single channel conductance of all K+ channels. Here we examine the mechanism of this large conductance. Comparison of the sequence of BK channels to lower-conductance K+ channels and to a crystallized bacterial K+ channel (MthK) revealed that BK channels have a ring of eight negatively charged glutamate residues at the entrance to the intracellular vestibule. This ring of charge, which is absent in lower-conductance K+ channels, is shown to double the conductance of BK channels for outward currents by increasing the concentration of K+ in the vestibule through an electrostatic mechanism. Removing the ring of charge converts BK channels to inwardly rectifying channels. Thus, a simple electrostatic mechanism contributes to the large conductance of BK channels.

Original languageEnglish (US)
Pages (from-to)9017-9022
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume100
Issue number15
DOIs
StatePublished - Jul 22 2003

ASJC Scopus subject areas

  • General

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