Article date: March 2004
By: H Kovalev, J M Quayle, T Kamishima, D Lodwick in Volume 141, Issue 5, pages 867-873
In this study, we have used Kir6.1/Kir6.2 chimeric proteins and current recordings to investigate the molecular basis of PNU‐37883A inhibition of cloned KATP channels.
Rat Kir6.1, Kir6.2 and Kir6.1/Kir6.2 chimeras were co‐expressed with either SUR2B or SUR1, following RNA injection into Xenopus oocytes, and fractional inhibition of KATP currents by 10 μM PNU‐37883A reported.
Channels containing Kir6.1/SUR2B were more sensitive to inhibition by PNU‐37883A than those containing Kir6.2/SUR2B (mean fractional inhibition: 0.70, cf. 0.07).
On expression with SUR2B, a chimeric channel with the Kir6.1 pore and the Kir6.2 amino‐ and carboxy‐terminal domains was PNU‐37883A insensitive (0.06). A chimera with the Kir6.1 carboxy‐terminus and Kir6.2 amino‐terminus and pore was inhibited (0.48). These results, and those obtained with other chimeras, suggest that the C‐terminus is an important determinant of PNU‐37883A inhibition of Kir6.1. Similar results were seen when constructs were co‐expressed with SUR1. Further chimeric constructs localised PNU‐37883A sensitivity to an 81 amino‐acid residue section in the Kir6.1 carboxy‐terminus.
Our data show that structural differences between Kir6.1 and Kir6.2 are important in determining sensitivity to PNU‐37883A. This compound may prove useful in probing the structural and functional differences between the two channel subtypes.
In this study, we have used Kir6.1/Kir6.2 chimeric proteins and current recordings to investigate the molecular basis of PNU‐37883A inhibition of cloned KATP channels.
Rat Kir6.1, Kir6.2 and Kir6.1/Kir6.2 chimeras were co‐expressed with either SUR2B or SUR1, following RNA injection into Xenopus oocytes, and fractional inhibition of KATP currents by 10 μM PNU‐37883A reported.
Channels containing Kir6.1/SUR2B were more sensitive to inhibition by PNU‐37883A than those containing Kir6.2/SUR2B (mean fractional inhibition: 0.70, cf. 0.07).
On expression with SUR2B, a chimeric channel with the Kir6.1 pore and the Kir6.2 amino‐ and carboxy‐terminal domains was PNU‐37883A insensitive (0.06). A chimera with the Kir6.1 carboxy‐terminus and Kir6.2 amino‐terminus and pore was inhibited (0.48). These results, and those obtained with other chimeras, suggest that the C‐terminus is an important determinant of PNU‐37883A inhibition of Kir6.1. Similar results were seen when constructs were co‐expressed with SUR1. Further chimeric constructs localised PNU‐37883A sensitivity to an 81 amino‐acid residue section in the Kir6.1 carboxy‐terminus.
Our data show that structural differences between Kir6.1 and Kir6.2 are important in determining sensitivity to PNU‐37883A. This compound may prove useful in probing the structural and functional differences between the two channel subtypes.
British Journal of Pharmacology (2004) 141, 867–873. doi:10.1038/sj.bjp.0705670
DOI: 10.1038/sj.bjp.0705670
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