GYGD pore motifs in neighbouring potassium channel subunits interact to determine ion selectivity.

Published

Journal Article

Cells maintain a negative resting membrane potential through the constitutive activity of background K+ channels. A novel multigene family of such K+ channels has recently been identified. A unique characteristic of these K+ channels is the presence of two homologous, subunit-like domains, each containing a pore-forming region. Sequence co-variations in the GYGD signature motifs of the two pore regions suggested an interaction between neighbouring pore domains. Mutations of the GYGD motif in the rat drk1 (Kv2.1) K+ channel showed that the tyrosine (Y) position was important for K+ selectivity and single channel conductance, whereas the aspartate (D) position was a critical determinant of open state stability. Tandem constructs engineered to mimic the GYGx-GxGD pattern seen in two-domain K+ channels delineated a co-operative intersubunit interaction between the Y and D positions, which determined ion selectivity, conductance and gating. In the bacterial KcsA K+ channel crystal structure, the equivalent aspartate residue (D80) does not directly interact with permeating K+ ions. However, the data presented here show that the D position is able to fine-tune ion selectivity through a functional interaction with the Y position in the neighbouring subunit. These data indicate a physiological basis for the extensive sequence variation seen in the GYGD motifs of two-domain K+ channels. It is suggested that a cell can precisely regulate its resting membrane potential by selectively expressing a complement of two-domain K+ channels.

Full Text

Duke Authors

Cited Authors

  • Chapman, ML; Krovetz, HS; VanDongen, AM

Published Date

  • January 1, 2001

Published In

Volume / Issue

  • 530 / Pt 1

Start / End Page

  • 21 - 33

PubMed ID

  • 11136855

Pubmed Central ID

  • 11136855

International Standard Serial Number (ISSN)

  • 0022-3751

Digital Object Identifier (DOI)

  • 10.1111/j.1469-7793.2001.0021m.x

Language

  • eng

Conference Location

  • England