Essential for maintaining normal cardiac rhythm in the developing heart and for neonatal survival (PubMed:33597309). Inhibits potassium and calcium currents in the cardiomyocytes, this assists in timely action potential repolarization and thereby maintains normal cardiac rhythm (PubMed:33597309). Mutants display highly specific cardiac arrhythmia and die by 15 days post-fertilization (dpf) (PubMed:33597309). Exhibit skipped ventricular beats, irregular beats and slower heart rate but their hearts are morphologically indistinguishable from wild-type counterparts (PubMed:33597309). Increased potassium and calcium currents observed in isolated cardiomyocytes (PubMed:33597309). Belongs to the TMEM161 family.