A novel ATP-dependent inward rectifier potassium channel expressed predominantly in glial cells.
We have isolated a novel inward rectifier K+ channel predominantly expressed in glial cells of the central nervous system. Its amino acid sequence exhibited 53% identity with ROMK1 and approximately 40% identity with other inward rectifier K+ channels. Xenopus oocytes injected with cRNA derived from this clone expressed a K+ current, which showed classical inward rectifier K+ channel characteristics. Intracellular Mg.ATP was required to sustain channel activity in excised membrane patches, which is consistent with a Walker type-A ATP-binding domain on this clone. We designate this new clone as KAB-2 (the second type of inward rectifying K+ channel with an ATP-binding domain). In situ hybridization showed KAB-2 mRNA to be expressed predominantly in glial cells of the cerebellum and forebrain. This is the first description of the cloning of a glial cell inward rectifier potassium channel, which may be responsible for K+ buffering action of glial cells in the brain.
Takumi
T
T
Department of Pharmacology II, Faculty of Medicine Osaka University, Japan.
Ishii
T
T
Horio
Y
Y
Morishige
K
K
Takahashi
N
N
Yamada
M
M
Yamashita
T
T
Kiyama
H
H
Sohmiya
K
K
Nakanishi
S
S
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism*; D016764:Cell Polarity; D002531:Cerebellum; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004553:Electric Conductivity; D017403:In Situ Hybridization; D008297:Male; D008969:Molecular Sequence Data; D009457:Neuroglia / Q000737:chemistry*; D009865:Oocytes; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying; D016548:Prosencephalon; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D014981:Xenopus
D018076:DNA, Complementary; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D012333:RNA, Messenger; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate