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Molecular cloning and functional expression of a novel brain‐specific inward rectifier potassium channel
Author(s) -
Kenichirou Morishige,
Naohiko Takahashi,
Arshad Jahangir,
Mitsuhiko Yamada,
Hidekazu Koyama,
Jill S. Zanelli,
Yoshihisa Kurachi
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)00483-8
Subject(s) - inward rectifier potassium ion channel , xenopus , complementary dna , cdna library , microbiology and biotechnology , potassium channel , biology , chemistry , biochemistry , biophysics , ion channel , gene , receptor
We have cloned a novel brain‐specific inward rectifier K + channel from a mouse brain cDNA library and designated it MB‐IRK3. The mouse brain cDNA library was screened using a fragment of the mouse macrophage inward rectifier K + channel (IRK1) cDNA as a probe. The amino acid sequence of MB‐IRK3 shares 61% and 64% identity to MB‐IRK1 and RB‐IRK2, respectively. Xenopus oocytes injected with cRNA derived from this clone expressed a potassium current which showed inward‐rectifying channel characteristics similar to MB‐IRK1 and RB‐IRK2 currents, but distinct from ROMK1 or GIRK1 current. However, the single channel conductance of MB‐IRK3 was ∼ 10 pS with 140 mM extracellular K + , which was distinct from that of MB‐IRK1 (20 pS). MB‐IRK3 mRNA expressed specifically in the forebrain, which clearly differed from MB‐IRK1 and RB‐IRK2 mRNAs. These results indicate that members of the IRK family with distinct electrophysiological properties express differentially and may play heterogenous functional roles in brain functions.