Nature 415, 1039–1042 (2002).
In this Letter, we reported that MEC-4d capped RNA produced currents statistically indistinguishable from those in water-injected oocytes. Those experiments included oocytes cultured in the presence and absence of 300 µM amiloride. On examining additional amiloride-treated oocytes, we find that injecting MEC-4d capped RNA alone can result in a statistically significant amiloride-sensitive current at -85 mV (P < 0.0001). Cells expressing MEC-4d produced amiloride-sensitive currents of -0.22 ± 0.03 µA (n = 53, range: -0.007 to -1.15 µA), compared to -0.005 ± 0.006 µA (n = 19, range: -0.06 to + 0.06 µA) for water-injected controls. Although these currents are similar in average size, voltage-dependence and time-dependence to those measured in cells co-expressing MEC-4d and MEC-10d, these results do not alter our conclusion that MEC-4 and MEC-10 form heteromeric channels, because MEC-10d increases the apparent affinity for amiloride of the MEC-4d/MEC-2 channel. Our new finding, however, suggests that MEC-4 forms homomeric channels when expressed alone. We also continue to find that co-expression of human stomatin or MEC-2(114-363) produces a small increase in MEC-4d current (P < 0.05).
The online version of the original article can be found at 10.1038/4151039a