Referenced in: none

Automatically associated channels: BKβ

Title: An epilepsy/dyskinesia-associated mutation enhances BK channel activation by potentiating Ca2+ sensing.

Authors: Junqiu Yang, Gayathri Krishnamoorthy, Akansha Saxena, Guohui Zhang, Jingyi Shi, Huanghe Yang, Kelli Delaloye, David Sept, Jianmin Cui

Journal, date & volume: Neuron, 2010 Jun 24 , 66, 871-83

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/20620873

Abstract
Ca(2+)-activated BK channels modulate neuronal activities, including spike frequency adaptation and synaptic transmission. Previous studies found that Ca(2+)-binding sites and the activation gate are spatially separated in the channel protein, but the mechanism by which Ca(2+) binding opens the gate over this distance remains unknown. By studying an Asp-to-Gly mutation (D434G) associated with human syndrome of generalized epilepsy and paroxysmal dyskinesia (GEPD), we show that a cytosolic motif immediately following the activation gate S6 helix, known as the AC region, mediates the allosteric coupling between Ca(2+) binding and channel opening. The GEPD mutation inside the AC region increases BK channel activity by enhancing this allosteric coupling. We found that Ca(2+) sensitivity is enhanced by increases in solution viscosity that reduce protein dynamics. The GEPD mutation alters such a response, suggesting that a less flexible AC region may be more effective in coupling Ca(2+) binding to channel opening.