STRUCTURE OF THE N-TERMINAL DOMAIN OF THE HUMAN-ERG POTASSIUM CHANNEL
[KCNH2_HUMAN] Defects in KCNH2 are the cause of long QT syndrome type 2 (LQT2) [MIM:613688]. Long QT syndromes are heart disorders characterized by a prolonged QT interval on the ECG and polymorphic ventricular arrhythmias. They cause syncope and sudden death in response to exercise or emotional stress. Deafness is often associated with LQT2.                        Defects in KCNH2 are the cause of short QT syndrome type 1 (SQT1) [MIM:609620]. Short QT syndromes are heart disorders characterized by idiopathic persistently and uniformly short QT interval on ECG in the absence of structural heart disease in affected individuals. They cause syncope and sudden death. 
[KCNH2_HUMAN] Pore-forming (alpha) subunit of voltage-gated inwardly rectifying potassium channel. Channel properties are modulated by cAMP and subunit assembly. Mediates the rapidly activating component of the delayed rectifying potassium current in heart (IKr). Isoform 3 has no channel activity by itself, but modulates channel characteristics when associated with isoform 1.
Publication Abstract from PubMed
The HERG voltage-dependent K+ channel plays a role in cardiac electrical excitability, and when defective, it underlies one form of the long QT syndrome. We have determined the crystal structure of the HERG K+ channel N-terminal domain and studied its role as a modifier of gating using electrophysiological methods. The domain is similar in structure to a bacterial light sensor photoactive yellow protein and provides the first three-dimensional model of a eukaryotic PAS domain. Scanning mutagenesis of the domain surface has allowed the identification of a hydrophobic "hot spot" forming a putative interface with the body of the K+ channel to which it tightly binds. The presence of the domain attached to the channel slows the rate of deactivation. Given the roles of PAS domains in biology, we propose that the HERG N-terminal domain has a regulatory function.
Crystal structure and functional analysis of the HERG potassium channel N terminus: a eukaryotic PAS domain.,Morais Cabral JH, Lee A, Cohen SL, Chait BT, Li M, Mackinnon R Cell. 1998 Nov 25;95(5):649-55. PMID:9845367
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.