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

Maria A. Schumacher, Andre F. Rivard, Hans Peter Bächinger, John P. Adelman

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Abstract

Small-conductance Ca2+-activated K+ channels (SK channels)1,2 are independent of voltage and gated solely by intracellular Ca2+. These membrane channels are heteromeric complexes that comprise pore-forming α-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 α-subunit immediately carboxy-terminal to the pore3,4. Channel opening is triggered when Ca2+ binds the EF hands in the N-lobe of CaM4. Here we report the 1.60 Å 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 α-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.

Original languageEnglish (US)
Pages (from-to)1120-1124
Number of pages5
JournalNature
Volume410
Issue number6832
DOIs
StatePublished - Apr 26 2001

ASJC Scopus subject areas

  • General

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    Schumacher, M. A., Rivard, A. F., Bächinger, H. P., & Adelman, J. P. (2001). Structure of the gating domain of a Ca2+-activated K+ channel complexed with Ca2+/calmodulin. Nature, 410(6832), 1120-1124. https://doi.org/10.1038/35074145