Cloning and functional expression of a novel isoform of ROMK inwardly rectifying ATP-dependent K+ channel, ROMK6 (Kir1.1f).
We have identified from rat kidney a novel isoform of ROMK/Kir1.1, designated ROMK6/Kir1.1f. ROMK6 was nearly identical to ROMK1, but possessed an 122-bp insertion in the 5' region. Its deduced amino acid sequence was shorter by 19 amino acids than that of ROMK1 in the amino-terminus. Unlike other previously reported ROMK isoforms, ROMK6 mRNA was ubiquitously expressed in various tissues, including kidney, brain, heart, liver, pancreas and skeletal muscle. Xenopus oocytes injected with ROMK6 cRNA expressed a Ba2+-sensitive weakly inwardly rectifying K+ current. These results indicate that ROMK6 is a novel functional K+ channel and might be involved in K+ secretion in various tissue.
Kondo
C
C
Department of Pharmacology II, Faculty of Medicine, Osaka University, Suita, Japan.
Isomoto
S
S
Matsumoto
S
S
Yamada
M
M
Horio
Y
Y
Yamashita
S
S
Takemura-Kameda
K
K
Matsuzawa
Y
Y
Kurachi
Y
Y
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D018076:DNA, Complementary; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000235:genetics*; D024661:Potassium Channels, Inwardly Rectifying; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014981:Xenopus
D018076:DNA, Complementary; C510692:Kcnj1 protein, rat; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D012333:RNA, Messenger; D000255:Adenosine Triphosphate