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| CLONING AND FUNCTIONAL-CHARACTERIZATION OF A NOVEL ATP-SENSITIVE POTASSIUM CHANNEL UBIQUITOUSLY EXPRESSED IN RAT-TISSUES, INCLUDING PANCREATIC-ISLETS, PITUITARY, SKELETAL-MUSCLE, AND HEART |
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| Author(s): INAGAKI N, TSUURA Y, NAMBA N, MASUDA K, GONOI T, HORIE M, SEINO Y, MIZUTA M, SEINO S |
| Source: JOURNAL OF BIOLOGICAL CHEMISTRY Volume: 270 Issue: 11 Pages: 5691-5694 Published: MAR 17 1995 |
| Times Cited: 269 References: 31 |
| Abstract: ATP-sensitive K+ (K-ATP) channels play a crucial role in coupling metabolic energy to the membrane potential of cells. We have isolated a cDNA encoding a novel member (uK(ATP)-1) of the inward rectifier K+ channel family from a rat pancreatic islet cDNA library, Rat uK(ATP)-1 is a 424-amino acid residue protein (M(r) = 47,960), Electrophysiological studies of uK(ATP)-1 expressed in Xenopus laevis oocytes show that uK(ATP)-1 is a weak rectifier and is blocked with Ba2+ ions, Single-channel patch clamp study of clonal human kidney epithelial cells (HEK293) transfected with uK(ATP)-1 cDNA reveals that uK(ATP)-1 closes in response to 1 mM ATP and has a single channel conductance of 70 +/- 2 picosiemens (n = 6), indicating that uK(ATP)-1 is an ATP-sensitive inward rectifier K+ channel. In addition, uK(ATP)-1 is activated by the K-ATP channel opener, diazoxide. RNA blot analysis shows that uK(ATP)-1 mRNA is expressed ubiquitously in rat tissues, including pancreatic islets, pituitary, skeletal muscle, and heart, suggesting that uK(ATP)-1 may play a physiological role as a link between the metabolic state and membrane K+ permeability of cells in almost every normal tissue. Since uK(ATP)-1 shares only 43-46% amino acid identity with members of previously reported inward rectifier K+ channel subfamilies, including ROMK1, IRK1, GIRK1, and cK(ATP)-1, uK(ATP)-1 is not an isoform of these subfamilies and, therefore, represents a new subfamily of the inward rectifier K+ channel family having two transmembrane segments. |
| Document Type: Note |
| Language: English |
Addresses:
1. CHIBA UNIV, SCH MED, CTR BIOMED SCI, DIV MOLEC MED, CHUO KU, CHIBA 260, JAPAN
2. KYOTO UNIV, SCH MED, DEPT INTERNAL MED 3, SAKYO KU, KYOTO 606, JAPAN
3. KYOTO UNIV, SCH MED, DEPT METAB & CLIN NUTR, SAKYO KU, KYOTO 606, JAPAN
4. CHIBA UNIV, PATHOGEN FUNGI & MICROBIAL TOXICOSES RES CTR, CHUO KU, CHIBA 260, JAPAN |
| Publisher: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 |
| Subject Category: Biochemistry & Molecular Biology |
| IDS Number: QM945 |
| ISSN: 0021-9258 |
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| | | | | | | | | Record from Web of Science® | | | | | | | | | |