POPDC2 and Bradycardia: Given that deletion or mutation of POPDC1 often leads to loss of POPDC2 membrane localization, and deletion of either POPDC isoform closely phenocopies one another with respect to HR variability and stress‐induced bradycardia, POPDC1 likely heterodimerizes with POPDC2 (Brand et al, 2014; Schindler et al, 2016b; Brand, 2019).