Domain-swapped chain connectivity and gated membrane access in a Fab-mediated crystal of the human TRAAK K+ channel.

ABSTRACT: TRAAK (TWIK-related arachidonic acid-stimulated K(+) channel, K2P4.1) K(+) ion channels are expressed predominantly in the nervous system to control cellular resting membrane potential and are regulated by mechanical and chemical properties of the lipid membrane. TRAAK channels are twofold symmetric, which precludes a direct extension of gating mechanisms that close canonical fourfold symmetric K(+) channels. We present the crystal structure of human TRAAK in complex with antibody antigen-binding fragments (Fabs) at 2.75-Å resolution. In contrast to a previous structure, this structure reveals a domain-swapped chain connectivity enabled by the helical cap that exchanges two opposing outer helices 180° around the channel. An unrelated conformational change of an inner helix seals a side ope

SUBMITTER: Brohawn SG 

PROVIDER: S-EPMC3568379 | biostudies-literature | 2013 Feb

REPOSITORIES: biostudies-literature