A far-red emitting fluorescent marker protein, mGarnet2, for microscopy and STED nanoscopy.

Here we present mGarnet2, a monomeric, far-red fluorescent marker protein derived from mRuby, with absorption and emission bands peaking at 598 and 671 nm, respectively. The protein shows excellent performance as a live-cell fusion marker for STED nanoscopy with 640 nm excitation and 780 nm depletion wavelengths.