The beta subunit of Kv1 channels: voltage-gated enzyme or safety switch?

The beta subunit of Kv1 channels at first appears to be a quirk of mother nature--a redox protein permanently co-opted into a K+ channel assembly in the central nervous system. The N-terminal cytoplasmic domain of the channel, T1, mediates its assimilation into the complex. Recent structural and biophysical characterization of the protein components of this assembly has been enlightening, but its principal physiological office is still in question. Here we re-examine the structural data with a view to providing a biological rationale for this unlikely partnership. A fresh interpretation of key structural features of beta and T1 provides incidental evidence that the main channel gate in the transmembrane region can be subverted by the cytosolic assembly as part of a cellular response to oxidative stress. A hypothetical model in which the T1-beta interaction modulates the channel by controlling a secondary gate in the cytosol is offered as a plausible means by which feedback regulation of Kv1 channels might be achieved.