Furthermore, myosin-5b binds to nuclear-encoded mitochondrial proteins and is directly involved in the transport of the voltage-gated potassium channel Kv1.5 protein in cardiomyocytes,19 as well as of glucose storage vesicles towards the plasma membrane in muscle cells.20 All these functions of MYO5b appear to be essential for cardiomyocyte maturation and subsequently for maintaining normal cardiac function in the adult heart, since MYO5b-KO mice develop arrhythmias at a young age, progressing to heart failure later on. Here, KCNA5 is linked to heart failure.