RGS12 interacts with the SNARE-binding region of the Cav2.2 calcium channel

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• GABAB receptor activation inhibits Cav2.2 calcium channels in dorsal root ganglion (DRG) neurons.
• This inhibition involves a tyrosine kinase that phosphorylates the alpha1 subunit, recruiting Regulator of G protein signaling 12 (RGS12).

Purpose of the Study:

• To investigate the binding interaction between RGS12 and the Cav2.2 calcium channel alpha1 subunit.
• To identify the specific region and phosphorylation sites involved in this interaction and its functional consequences.

Main Methods:

• Protein overlay and surface plasmon resonance binding assays using recombinant RGS12 PTB domain and synprint region peptides.
• Electrophysiological experiments involving microinjection of DRG neurons with synprint-derived peptides.
• Co-immunoprecipitation to precipitate RGS12 using synprint peptides.

Main Results:

• RGS12 binds to the synprint region (amino acids 726-985) of the Cav2.2 alpha1 subunit in a tyrosine phosphorylation-dependent manner.
• Tyrosine phosphorylation of Tyr-804 within the synprint region is crucial for RGS12 binding and alters the desensitization rate of channel inhibition.
• The binding interaction differs from canonical PTB domain interactions and involves a conserved tyrosine residue.

Conclusions:

• The synprint region of the Cav2.2 calcium channel alpha1 subunit serves as a binding site for RGS12, mediated by tyrosine phosphorylation at Tyr-804.
• This interaction is critical for the voltage-independent modulation of Cav2.2 channel activity by GABAB receptors.
• The findings highlight a novel mechanism for calcium channel regulation and suggest broader roles for the synprint region in channel modulation.