In the adult rat heart, ERG1 is primarily expressed in the transverse tubular system, whereas KCNQ1 is more widely distributed in both the peripheral sarcolemma and T tubules.
KCNQ1 and ERG1 potassium channels have distinct subcellular localizations in rat cardiac myocytes, with ERG1 restricted to the T-tubular system and KCNQ1 more widely distributed, positioning them close to Ca2+ channels for maximal repolarizing effect.
In the heart, several K(+) channels are responsible for the repolarization of the cardiac action potential, including transient outward and delayed rectifier K(+) currents. In the present study, the cellular and subcellular localization of the two delayed rectifier K(+) channels, KCNQ1 and ether-a-go-go-related gene-1 (ERG1), was investigated in the adult rat heart. Confocal immunofluorescence microscopy of atrial and ventricular cells revealed that whereas KCNQ1 labeling was detected in both the peripheral sarcolemma and a structure transversing the myocytes, ERG1 immunoreactivity was confined to the latter. Immunoelectron microscopy of atrial and ventricular myocytes showed that the ERG1 channel was primarily expressed in the transverse tubular system and its entrance, whereas KCNQ1 was detected in both the peripheral sarcolemma and in the T tubules. Thus, whereas ERG1 displays a very restricted subcellular localization pattern, KCNQ1 is more widely distributed within the cardiac cells. The localization of these K(+) channels to the transverse tubular system close to the Ca(2+) channels renders them with maximal repolarizing effect.
Rasmussen et al. (Fri,) reported a other. Subcellular localization of KCNQ1 and ERG1 was evaluated on Subcellular localization of KCNQ1 and ERG1. In the adult rat heart, ERG1 is primarily expressed in the transverse tubular system, whereas KCNQ1 is more widely distributed in both the peripheral sarcolemma and T tubules.
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