Selective fluorophore-assisted light inactivation of voltage-gated calcium channels

Fluorophore-assisted light inactivation (FALI) is an investigative tool to inactivate fluorescently labeled proteins by a mechanism of in situ photodestruction. We found that Cav 1.2 (L-type) and Cav 3.1 (T-type) calcium channels, labeled by genetic fusion with GFP derivatives, show differential sensitivity to FALI. Specifically, FALI silences Cav 1.2 calcium channels containing EYFP-labeled α 1C subunits but does not affect the EYFP-α 1G Cav 3.1 calcium channels or Cav 1.2 channels containing EYFP-labeled β subunits. Our findings limit the applicability of acceptor photobleaching for the measurements of FRET but open an opportunity to combine the fluorescent imaging of the live cell expressing labeled calcium channels with selective functional inactivation of their specific subsets.