Cortisone dissociates the Shaker family K+ channels from their beta subunits.
The Shaker family voltage-dependent potassium channels (Kv1) are expressed in a wide variety of cells and are essential for cellular excitability. In humans, loss-of-function mutations of Kv1 channels lead to hyperexcitability and are directly linked to episodic ataxia and atrial fibrillation. All Kv1 channels assemble with beta subunits (Kv betas), and certain Kv betas, for example Kv beta 1, have an N-terminal segment that closes the channel by the N-type inactivation mechanism. In principle, dissociation of Kv beta 1, although never reported, should eliminate inactivation and thus potentiate Kv1 current. We found that cortisone increases rat Kv1 channel activity by binding to Kv beta 1. A crystal structure of the Kv beta-cortisone complex was solved to 1.82-A resolution and revealed novel cortisone binding sites. Further studies demonstrated that cortisone promotes dissociation of Kv beta. The new mode of channel modulation may be explored by native or synthetic ligands to fine-tune cellular excitability.
Pan
Yaping
Y
Department of Physiology and Cellular Biophysics, Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, New York 10032, USA.
Weng
Jun
J
Kabaleeswaran
Venkataraman
V
Li
Huiguang
H
Cao
Yu
Y
Bhosle
Rahul C
RC
Zhou
Ming
M
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive / Q000187:drug effects; D003348:Cortisone / Q000737:chemistry / Q000494:pharmacology*; D018360:Crystallography, X-Ray; D006801:Humans; D051663:Kv1.2 Potassium Channel / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D051637:Shaker Superfamily of Potassium Channels / Q000187:drug effects* / Q000378:metabolism; D014981:Xenopus
D051663:Kv1.2 Potassium Channel; D051637:Shaker Superfamily of Potassium Channels; D003348:Cortisone