The latter study is of special relevance because it has documented that the increase in IF1 in pathological cardiac hypertrophy, in agreement with similar findings by others [18], results in the formation of nonproductive ATP synthase tetramers, as assessed by chemical cross-linking mass spectrometry analysis of hypertrophied hearts [17], which also agrees with recent cryo-EM structures of the tetrameric IF1-inhibited ATP synthase isolated from hearts of other mammalian species [19,20]. Here, ATP5IF1 is linked to cardiac hypertrophy.