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Gain of function mutants: ion channels and G protein-coupled receptors
1Division of Biology, California Institute of Technology, Pasadena 91125, USA. Lester@caltech.edu
Abstract:
Many ion channels and receptors display striking phenotypes for gain-of-function mutations but milder phenotypes for null mutations. Gain of molecular function can have several mechanistic bases: selectivity changes, gating changes including constitutive activation and slowed inactivation, elimination of a subunit that enhances inactivation, decreased drug sensitivity, changes in regulation or trafficking of the channel, or induction of apoptosis. Decreased firing frequency can occur via increased function of K+ or Cl- channels. Channel mutants also cause gain-of-function syndromes at the cellular and circuit level; of these syndromes, the cardiac long-QT syndromes are explained in a more straightforward way than are the epilepsies. G protein-coupled receptors are also affected by activating mutations.
Insights
Gain-of-function mutations in ion channels and receptors often cause more severe disease than null mutations. These mutations can alter channel gating, drug sensitivity, or regulation, leading to various cellular and circuit-level syndromes.
Area of Science:
- Molecular biology
- Neuroscience
- Pharmacology
Background:
- Ion channels and receptors are crucial for cellular function.
- Gain-of-function mutations can lead to significant physiological alterations.
Purpose of the Study:
- To explore the mechanistic bases of gain-of-function mutations in ion channels and receptors.
- To understand the resulting cellular and circuit-level syndromes.
Main Methods:
- Review of existing literature on ion channel and receptor mutations.
- Analysis of mechanistic explanations for gain-of-function phenotypes.
Main Results:
- Gain-of-function mutations can arise from changes in selectivity, gating, subunit interactions, drug sensitivity, regulation, or apoptosis induction.
- These mutations can lead to syndromes like cardiac long-QT and epilepsies.
- Activating mutations also affect G protein-coupled receptors.
Conclusions:
- Gain-of-function mutations represent a significant area of study in channelopathies and related disorders.
- Understanding these mechanisms is key to developing targeted therapies.