Molecular analysis of the subtype-selective inhibition of cloned KATP channels by PNU-37883A.
1. 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 K(ATP) channels. 2. 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 K(ATP) currents by 10 microm PNU-37883A reported. 3. 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). 4. 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. 5. 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.
Kovalev
H
H
Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, PO Box 65, Leicester LE2 7LX.
Quayle
J M
JM
Kamishima
T
T
Lodwick
D
D
D000218:Adamantane / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000235:genetics / Q000502:physiology; D000818:Animals; D003001:Cloning, Molecular / Q000187:drug effects / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D005260:Female; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology*; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D015221:Potassium Channels; D051381:Rats; D014982:Xenopus laevis
D008565:Membrane Proteins; D009025:Morpholines; D026902:Potassium Channel Blockers; D015221:Potassium Channels; C117780:mitochondrial K(ATP) channel; C082658:U 37883A; D000255:Adenosine Triphosphate; D000218:Adamantane