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Updated: Aug 10, 2026

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells
Published on: October 2, 2010
Functional characterization of a prokaryotic Kir channel
Decha Enkvetchakul1, Jaya Bhattacharyya, Iana Jeliazkova
1Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Abstract:
The Kir gene family encodes inward rectifying K+ (Kir) channels that are widespread and critical regulators of excitability in eukaryotic cells. A related gene family (KirBac) has recently been identified in prokaryotes. While a crystal structure of one member, Kir-Bac1.1, has been solved, there has been no functional characterization of any KirBac gene products. Here we present functional characterization of KirBac1.1 reconstituted in liposomes. Utilizing a 86Rb+ uptake assay, we demonstrate that KirBac1.1 generates a K+ -selective permeation path that is inhibited by extraliposomal Ba2+ and Ca2+ ions. In contrast to KcsA (an acid-activated bacterial potassium channel), KirBac1.1 is inhibited by extraliposomal acid (pKa approximately 6). This characterization of KirBac1.1 activity now paves the way for further correlation of structure and function in this model Kir channel.
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