Structure of the Cytoplasmic β Subunit--T1 Assembly of Voltage-Dependent K ⁺ Channels

TLDR

The structure of the cytoplasmic assembly of voltage‑dependent K⁺ channels was solved by X‑ray crystallography at 2.1 Å resolution. The four‑fold symmetric T1⁴β⁴ complex, comprising the α subunit’s cytoplasmic T1 domain and the oxidoreductase β subunit, has T1 domains oriented toward the pore and β subunits toward the cytoplasm, with the pore communicating to the cytoplasm through lateral negatively charged openings that allow inactivation peptides to reach their site of action.

Abstract

The structure of the cytoplasmic assembly of voltage-dependent K + channels was solved by x-ray crystallography at 2.1 angstrom resolution. The assembly includes the cytoplasmic (T1) domain of the integral membrane α subunit together with the oxidoreductase β subunit in a fourfold symmetric T1 4 β 4 complex. An electrophysiological assay showed that this complex is oriented with four T1 domains facing the transmembrane pore and four β subunits facing the cytoplasm. The transmembrane pore communicates with the cytoplasm through lateral, negatively charged openings above the T1 4 β 4 complex. The inactivation peptides of voltage-dependent K + channels reach their site of action by entering these openings.