Key result
Lq2 blocks the ROMK1 channel pore using the same interaction surface as other K+ channels.
The finding that Lq2 uses the same interaction surface to block different classes of K+ channels supports the concept that these channels share a similar K+-selective pore structure despite having different gates.
Supports conserved K+ pore structure across families; leaves open selective ROMK1 targeting for clinical use.
We have purified a protein inhibitor of an inward-rectifier K+ channel, ROMK1, from the venom of the scorpion Leiurus quinquestriatus var. hebraeus. The inhibitor is Lq2, a previously discovered blocker of voltage- and Ca2+-activated K+ channels. Mutations were made on the channel and the inhibitor, and the resulting effects were examined using an electrophysiological assay. The data show that Lq2 blocks the pore of ROMK1, and that the interaction surface on Lq2 is the same for binding to inward-rectifier, voltage-activated, or Ca2+-activated K+ channels. These findings support the notion that different classes of K+ channels have different gates but a similar K+-selective pore structure.
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Lü et al. (1997) studied this question. Lq2 (scorpion venom protein inhibitor) was evaluated on Electrophysiological assay of ROMK1 channel block. Lq2 blocks the pore of the inward-rectifier K+ channel ROMK1, utilizing the same interaction surface as for voltage- and Ca2+-activated K+ channels.
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