Plays a role in cardiac repolarization possibly by stabilizing membrane expression of the potassium channel kcnh6a/zerg, or by assisting its synthesis, folding or export from the endoplasmic reticulum, in a heat shock protein-dependent manner. Probably located in the endoplasmic reticulum and/or possibly the cis-Golgi apparatus. Morpholino knockdown of the protein results in abnormal contractility and looping in developing heart. Morphants show prolonged duration of cardiac action potentials, occasional 2:1 atrioventricular block and slowed conduction velocity (PubMed:25281747).