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Cloning provides evidence for a family of inward rectifier and G‐protein coupled K + channels in the brain
Author(s) -
Lesage Florian,
Duprat Fabrice,
Fink Michel,
Guillemare Eric,
Coppola Thierry,
Lazdunski Michel,
Hugnot Jean-Philippe
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)01007-2
Subject(s) - g protein coupled inwardly rectifying potassium channel , inward rectifier potassium ion channel , xenopus , amino acid , pleckstrin homology domain , g protein , biology , peptide sequence , microbiology and biotechnology , chemistry , gene , genetics , receptor , signal transduction , ion channel
MbIRK3, mbGIRK2 and mbGIRK3 K + channels cDNAs have been cloned from adult mouse brain. These eDNAs encode polypeptides of 445, 414 and 376 amino acids, respectively, which display the hallmarks of inward rectifier K + channels, i.e. two hydrophobic membrane‐spanning domains M1 and M2 and a pore‐forming domain H5. MbIRK3 shows around 65% amino acid identity with IRK1 and rbIRK2 and only 50% with ROMK1 and GIRK1. On the other hand, mbGIRK2 and mbGIRK3 are more similar to GIRK1 (60%) than to ROMK1 and IRK1 (50%). Northern blot analysis reveals that these three novel clones are mainly expressed in the brain. Xenopus oocytes injected with mbIRK3 and mbGIRK2 cRNAs display inward rectifier K + ‐selective currents very similar to IRK1 and GIRK1, respectively. As expected from the sequence homology, mbGIRK2 cRNA directs the expression of G‐protein coupled inward rectifyer K + channels which has been observed through their functional coupling with co‐expressed δ‐opioid receptors. These results provide the first evidence that the GIRK family, as the IRK family, is composed of multiple genes with members specifically expressed in the nervous system.