Two-pore cation (TPC) channel: not a shorthanded one

Area of Science:

• Plant molecular biology
• Ion channel biophysics
• Cellular signaling

Background:

• Two-pore cation (TPC) channels, including plant TPC1 (slow vacuolar or SV channel), form dimers in acidic intracellular compartments like vacuoles.
• SV channels exhibit high permeability to cations (Na+, K+, Mg2+, Ca2+) but are typically inactive, requiring high cytosolic Ca2+ and positive voltages for activation.
• Their activity is modulated by cytosolic and vacuolar ions (Ca2+, Mg2+, H+), maintaining low open probability to prevent harmful Ca2+ release.

Purpose of the Study:

• To review recent breakthroughs in understanding plant TPC1 channel function.
• To explore the molecular mechanisms of voltage and Ca2+ gating revealed by the crystal structure.
• To highlight the role of TPC1 in systemic Ca2+ signaling and establish a new perspective.

Main Methods:

• Review of recent literature, focusing on functional and structural studies of plant TPC1.
• Analysis of crystal structure data to elucidate gating mechanisms.
• Integration of findings on TPC1's role in Ca2+ signaling pathways.

Main Results:

• The crystal structure of plant TPC1 reveals molecular details of voltage and Ca2+ gating.
• TPC1 plays an essential role in systemic Ca2+ signaling, challenging previous notions of its limited function.
• Understanding TPC1 gating provides insights into localized and systemic calcium dynamics.

Conclusions:

• Recent findings significantly advance our understanding of plant TPC1 channel function and regulation.
• TPC1 is crucial for both local and systemic calcium signaling, with implications for plant physiology.
• This review sets a new framework for studying TPC1-mediated calcium signaling in plants.