Mutations in ion channels have been implicated in the formation of long QT syndrome (LQTS). However, Mohler et al. have recently uncovered a role for ankyrin-B, a non-ion channel protein, in type IV LQTS. Calcium signalling is altered, and the functions of several channels and pumps that normally interact with wild-type ankyrin-B are impaired in the presence of mutant ankyrin-B. The authors suggest that by disrupting the functions of these channels, a new mechanism has been uncovered that can lead to cardiac myopathy.