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October 1, 2002The Journal of PhysiologyOpen Access

Molecular mechanism of a COOH‐terminal gating determinant in the ROMK channel revealed by a Bartter's disease mutation

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Population

In vitro models of ROMK channel

Design

Preclinical

Authors

TFThomas P. FlaggDYDana YooCSChristopher M. Sciortino

Discussion

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Overview

Elucidates interdomain control of ROMK pH gating in Bartter's; leaves open whether targeting this interaction offers therapeutic strategies.

Key Points

  • To determine the molecular mechanism by which a COOH-terminal truncation in the ROMK channel disrupts pH-dependent gating and causes Bartter's disease.
  • Evaluated channel gating and pH sensitivity across truncation mutants and suppressor mutations within the cytoplasmic NH2-terminal pH sensor.
  • Tested functional recovery using trans addition of the cognate peptide and examined physical domain associations via in vitro protein-protein binding assays with bacterial fusion proteins.
  • Truncating the extreme COOH-terminus shifted the channel's pKa toward alkaline values, resulting in complete channel inactivation under normal physiological pH.
  • Channel gating was functionally restored either by introducing suppressor mutations into the NH2-terminal pH sensor or by adding the cognate peptide in trans.
  • In vitro binding assays demonstrated a specific physical interdomain interaction between the cytoplasmic NH2- and COOH-terminal domains.

Structured PICO

P
Population
In vitro models of ROMK channel (bacterial fusion proteins expressing NH2- and COOH-terminal cytoplasmic domains)
I
Intervention
Mutational analysis (truncation of extreme COOH-terminus, suppressor mutations within pH sensor, trans addition of cognate peptide)
O
Outcome
pH-dependent gating and channel inactivationsurrogate

Identifies a specific interdomain interaction in the ROMK channel that regulates pH-dependent gating, providing mechanistic insight into channel defects associated with Bartter's disease.

Cite This Study

Flagg et al. (2002) studied this question.

synapsesocial.com/papers/6a962011fb86bd36df01c679https://doi.org/10.1113/jphysiol.2002.027581
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Also Consider

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