Kir1.1 channels
| Channel name | Kir1.1 |
| Description | Inwardly rectifying potassium channel Kir1.1 subunit |
| Other names | Kir1.1, ROMK, ROMK1 |
| Molecular information | Human (KCNJ1): 391aa, Locus ID: 3758, GenBank: U12541, NM_000220, PMID: 7929082,1 chr. 11q24 |
| Rat (Kcnj1): 391aa, Locus ID: 24521, GenBank: X72341, NM_017023, PMID: 7680431,2 chr. 8q21 | |
| Mouse (Kcnj1): 372aa, Locus ID: 56379, GenBank: AF012834 (see “Comments”), NM_019659, PMID: 7611454,3 89801344,4 chr. 9A | |
| Associated subunits | Na+/H+ exchange regulatory factor 2 (NHERF2) (not required for function5) |
| Functional assays | Voltage-clamp |
| Current | Inwardly rectifying K+ current |
| Conductance | 47pS (285 mM K+), 40pS (140 mM K+) |
| Ion selectivity | K+ |
| Activation | Not established |
| Inactivation | Intracellular acidification |
| Activators | None |
| Gating inhibitors | None |
| Blockers | Nonselective: Ba2+, Cs+ |
| Radioligands | None |
| Channel distribution | Kidney (apical membranes in cortex and outer medulla), RT-PCR shows transcripts in skeletal muscle, pancreas, spleen, brain, heart, and liver |
| Physiological functions | K+ secretion (Kir1.1a, Kir1.1c, distal renal tubule), K+ recycling (Kir1.1b, thick ascending limb of loop of Henle) |
| Mutations and pathophysiology | Bartter's syndrome6 |
| Pharmacological significance | Not established |
| Comments | Six splice variants exist, denoted as Kir1.1a, Kir1.1b, Kir1.1c, Kir1.1d, Kir1.1e, and Kir1.1f |
aa, amino acids; chr., chromosome; RT-PCR, reverse transcriptase-polymerase chain reaction.
↵1. Shuck ME, Bock JH, Benjamin CW, Tsai TD, Lee KS, Slightom JL, and Bienkowski MJ (1994) Cloning and characterization of multiple forms of the human kidney ROM-K potassium channel. J Biol Chem 269:24261-24270
↵2. Ho K, Nichols CG, Lederer WJ, Lytton J, Vassilev PM, Kanazirska MV, and Hebert SC (1993) Cloning and expression of an inwardly rectifying ATP-regulated potassium channel. Nature (Lond) 362:31-38
↵3. Boim MA, Ho K, Shuck ME, Bienkowski MJ, Block JH, Slightom JL, Yang Y, Brenner BM, and Hebert SC (1995) ROMK inwardly rectifying ATP-sensitive K+ channel. II. Cloning and distribution of alternative forms. Am J Physiol 268:F1132-F1140
↵4. Kondo C, Isomoto S, Matsumoto S, Yamada M, Horio Y, Yamashita S, Takemura-Kameda K, Matsuzawa Y, and Kurachi Y. (1996) Cloning and functional expression of a novel isoform of ROMK inwardly rectifying ATP-dependent K+ channel, ROMK6 (Kir1.1f). FEBS Lett 399:122-126
↵5. Yoo D, Flagg TP, Olsen O, Raghuram V, Foskett JK, and Welling PA (2004) Assembly and trafficking of a multiprotein ROMK (Kir 1.1) channel complex by PDZ interactions. J Biol Chem 279:6863-6873
↵6. Schwalbe RA, Bianchi L, Accili EA, and Brown AM (1998) Functional consequences of ROMK mutants linked to antenatal Bartter's syndrome and implications for treatment. Hum Mol Genet 7:975-980