A rich conformational palette underlies human Ca_V2.1-channel availability

Area of Science:

• Neuroscience
• Molecular Biology
• Biophysics

Background:

• Calcium_V2.1 (P/Q-type) channels mediate neurotransmitter release.
• Voltage-dependent inactivation (VDI) of these channels impacts synaptic plasticity.
• The precise voltage sensing mechanism of Ca_V2.1 channels remains elusive.

Purpose of the Study:

• To elucidate the voltage-dependent structural dynamics of Ca_V2.1 channels.
• To characterize the roles of individual voltage-sensor domains (VSDs) in channel gating and inactivation.
• To understand how auxiliary subunits modulate channel function.

Main Methods:

• Voltage-clamp fluorometry to optically track VSD movements.
• Kinetic modeling to analyze channel gating mechanisms.
• Characterization of VSDs' differential voltage sensitivities.

Main Results:

• Ca_V2.1 VSDs exhibit distinct voltage sensitivities.
• VSD-I directly controls channel opening and switches between functional modes linked to VDI.
• VSD-II is voltage-insensitive, while VSD-III and VSD-IV respond to more negative potentials.
• Auxiliary β-subunits regulate VSD-I coupling and conversion kinetics.

Conclusions:

• Ca_V2.1 channel gating and VDI involve complex, differential movements of VSDs.
• VSD-I plays a central role in linking voltage changes to channel opening and synaptic release.
• Understanding these mechanisms is crucial for insights into synaptic plasticity, learning, and memory.