When is a hydrophobic gate not a hydrophobic gate?

Area of Science:

• Biophysics
• Molecular Biology
• Ion Channel Physiology

Background:

• Ion channel flux is typically controlled by steric occlusion of the pore.
• Alternatively, ion permeation can be blocked by desolvation barriers formed by hydrophobic residues.
• Hydrophobic gating involves transitions between wet and dry states to close channels without physical constriction.

Purpose of the Study:

• To formally define hydrophobic gating.
• To differentiate true hydrophobic gating from other mechanisms involving hydrophobic residues or lipids.
• To outline best practices for identifying hydrophobic gates.

Main Methods:

• Conceptual analysis and literature review.
• Comparison of different ion channel gating mechanisms.
• Discussion of experimental identification strategies.

Main Results:

• The term "hydrophobic gating" is often used broadly, deviating from its original mechanistic definition.
• Distinguishing true hydrophobic gating from steric closure is crucial for accurate understanding.
• Clear criteria are needed for identifying hydrophobic gating.

Conclusions:

• Hydrophobic gating is a specific mechanism involving desolvation barriers.
• Precise definition and identification methods are essential for advancing ion channel research.
• Clarifying the terminology ensures accurate interpretation of experimental findings.