A privileged ER compartment for post-translational heteromeric assembly of an ion channel.

Mechanisms underlying heterotypic subunit assembly of ion channels and other oligomeric assemblies are poorly understood. In the human heart, heteromeric assembly of two isoforms encoded by the () is essential for the normal function of cardiac I in ventricular repolarization, with loss of hERG1b contributing to arrhythmias associated with long QT-syndrome. While hERG1a homomers traffic efficiently to the plasma membrane, hERG1b homomers are retained in the endoplasmic reticulum (ER).