Structure of the gating domain of a Ca2+-activated K+ channel complexed with Ca2+/calmodulin.

Published

Journal Article

Small-conductance Ca2+-activated K+ channels (SK channels) are independent of voltage and gated solely by intracellular Ca2+. These membrane channels are heteromeric complexes that comprise pore-forming alpha-subunits and the Ca2+-binding protein calmodulin (CaM). CaM binds to the SK channel through the CaM-binding domain (CaMBD), which is located in an intracellular region of the alpha-subunit immediately carboxy-terminal to the pore. Channel opening is triggered when Ca2+ binds the EF hands in the N-lobe of CaM. Here we report the 1.60 A crystal structure of the SK channel CaMBD/Ca2+/CaM complex. The CaMBD forms an elongated dimer with a CaM molecule bound at each end; each CaM wraps around three alpha-helices, two from one CaMBD subunit and one from the other. As only the CaM N-lobe has bound Ca2+, the structure provides a view of both calcium-dependent and -independent CaM/protein interactions. Together with biochemical data, the structure suggests a possible gating mechanism for the SK channel.

Full Text

Duke Authors

Cited Authors

  • Schumacher, MA; Rivard, AF; Bächinger, HP; Adelman, JP

Published Date

  • April 26, 2001

Published In

Volume / Issue

  • 410 / 6832

Start / End Page

  • 1120 - 1124

PubMed ID

  • 11323678

Pubmed Central ID

  • 11323678

International Standard Serial Number (ISSN)

  • 0028-0836

Digital Object Identifier (DOI)

  • 10.1038/35074145

Language

  • eng

Conference Location

  • England