Cloning and characterization of multiple forms of the human kidney ROM-K potassium channel.

Shuck, Mary E.; Bock, Jeffery H.; Benjamin, Christopher W.; Tsai, T. D.; Lee, K. S.; Slightom, Jerry L.; Bienkowski, Michael J.

doi:10.1016/s0021-9258(19)51076-6

Cited by 109 publications

(7 citation statements)

References 36 publications

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“…Sequence alignment of the pore region from different cloned potassium channels. Shaker (Kv1.1;Tempel et al, 1987), Kv1.1 (Baumann et al, 1988), Kv2.1 (Frech et al, 1989, and Kv3.1(Yokoyama et al, 1989) encode voltagegated K ϩ channels.ROMK1 (Kir1.1a; Ho et al, 1993), ROMK2 (Kir1.1b; Zhou et al, 1994), and ROMK3 (Kir1.1c;Shuck et al, 1994) are ATP-activated weak inward rectifiers cloned from kidney. IRK1 (Kir2.1;Kubo et al, 1993a), rbIRK2 (Kir2.2;Koyama et al, 1994), and mbIRK3 (Kir2.3;Morishige et al, 1994) are cloned from a mouse macrophage cell line, rabbit brain, and mouse brain, respectively, and highly expressed in heart, brain, and skeletal muscle; these channels exhibit steep inward rectification.…”

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confidence: 99%

A Conserved Arginine Residue in the Pore Region of an Inward Rectifier K Channel (IRK1) as an External Barrier for Cationic Blockers

Sabirov

Tominaga

Miwa

et al. 1997

The Journal of General Physiology

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The number, sign, and distribution of charged residues in the pore-forming H5 domain for inward-rectifying K channels (IRK1) are different from the otherwise homologous H5 domains of other voltage-gated K channels. We have mutated Arg148, which is perfectly conserved in all inward rectifiers, to His in the H5 of IRK1 (Kir2.1). Channel activity was lost by the mutation, but coexpression of the mutant (R148H) along with the wild-type (WT) mRNA revealed populations of channels with reduced single-channel conductances. Long-lasting and flickery sublevels were detected exclusively for the coexpressed channels. These findings indicated that the mutant subunit formed hetero-oligomers with the WT subunit. The permeability ratio was altered by the mutation, while the selectivity sequence (K+ > Rb+ > NH4 + >> Na+) was preserved. The coexpression made the IRK1 channel more sensitive to extracellular block by Mg2+ and Ca2+, and turned this blockade from a voltage-independent to a -dependent process. The sensitivity of the mutant channels to Mg2+ was enhanced at higher pH and by an increased ratio of mutant:WT mRNA, suggesting that the charge on the Arg site controlled the sensitivity. The blocking rate of open channel blockers, such as Cs+ and Ba2+, was facilitated by coexpression without significant change in the steady state block. Evaluation of the electrical distance to the binding site for Mg2+ or Ca2+ and that to the barrier peak for block by Cs+ or Ba2+ suggest that Arg148 is located between the external blocking site for Mg2+ or Ca2+ and the deeper blocking site for Cs+ or Ba2+ in the IRK1 channel. It is concluded that Arg148 serves as a barrier to cationic blockers, keeping Mg2+ and Ca2+ out from the electric field of the membrane.

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confidence: 99%

A Conserved Arginine Residue in the Pore Region of an Inward Rectifier K Channel (IRK1) as an External Barrier for Cationic Blockers

Sabirov

Tominaga

Miwa

et al. 1997

The Journal of General Physiology

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“…ROMK gene. Previous studies have demonstrated that the gene encoding human ROMK produces 5 distinct transcripts (ROMK 1-5) by differential splicing of its 5 exons [11,12]. All 5 transcripts share an exon 5 that encodes most of the ROMK protein.…”

Section: Mutation Analysismentioning

confidence: 99%

Analysis of renal tubular electrolyte transporter genes in seven patients with hypokalemic metabolic alkalosis

Fukuyama¹,

Okudaira²,

Yamazato³

et al. 2003

Kidney International

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“…ROMK knockout (KO) mice show a similar phenotype to Bartter's syndrome of salt wasting and dehydration due to reduced Na-K-2Cl-cotransporter activity in the TAL (10). Three major ROMK isoforms were identified in the kidney: ROMK (1-3), with different lengths of the NH 2 terminal (12,26,28). ROMK2 has the shortest NH 2 terminal, whereas ROMK1 adds an additional 19 (rat) or 20 (mouse) residues.…”

Section: Introductionmentioning

confidence: 99%

Urinary bladder hypertrophy characteristic of male ROMK Bartter’s mice does not occur in female mice

Kim

Guo

et al. 2018

American Journal of Physiology-Regulatory, Integrative and Comp

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The renal outer medullary potassium channel (ROMK; K1.1) plays an important role in Na and K homeostasis. ROMK knockout (KO) mice show a similar phenotype to Bartter's syndrome of salt wasting and dehydration due to reduced Na-2Cl-K-cotransporter activity but not in ROMK1 KO mice. ROMK KO mice also show hydronephrosis; however, the mechanism of this phenotype has not been understood. We have previously demonstrated a gender-sex difference in hydronephrosis and PGE production in ROMK KO mice. In this study we compared the gender-sex difference in bladder hypertrophy and hydronephrosis in ROMK KO mice. The bladder weight, bladder capacity, and the thickness of urothelium in male ROMK KO showed average increased two to approximately fourfold greater than wild-type (WT) mice, but there was no difference in either female or ROMK1 KO mice. The thickness of the urothelium was 648.8 ± 33.2 µm vs. 302.7 ± 16.5 µm ( P < 0.001) and the detrusor muscle 1,940.7 ± 98.9 µm vs. 1,308.2 ± 102.1 µm ( P = 0.013), respectively, in 12-mo male ROMK KO mice compared with the same age WT mice. Western blotting detected ROMK expression at 45~48 kDa, and both ROMK1 and ROMK2 mRNA were detected by quantitative PCR in the bladder. Immunofluorescence staining showed ROMK stained in the bladder, ureter, and urethra in WT but not in KO. In addition, there was a correlation between the severity of hydronephrosis and the bladder weight in male but not in female ROMK KO mice. In conclusion, ROMK expressed in the urinary tract at both protein and mRNA levels; significant enlargement and hypertrophy of the bladder may contribute to hydronephrosis in male ROMK KO mice.

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Cloning and characterization of multiple forms of the human kidney ROM-K potassium channel.

Cited by 109 publications

References 36 publications

A Conserved Arginine Residue in the Pore Region of an Inward Rectifier K Channel (IRK1) as an External Barrier for Cationic Blockers

A Conserved Arginine Residue in the Pore Region of an Inward Rectifier K Channel (IRK1) as an External Barrier for Cationic Blockers

Analysis of renal tubular electrolyte transporter genes in seven patients with hypokalemic metabolic alkalosis

Urinary bladder hypertrophy characteristic of male ROMK Bartter’s mice does not occur in female mice

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