The authors note that that in the constructs EcadTSMod, EcadTSModΔcyto, and EcadTSModΔmTFP, the Förster resonance energy transfer (FRET) acceptor fluorophore was monomeric enhanced yellow fluorescent protein (mEYFP)-not Venus as was originally reported. The photophysical properties of mEYFP and Venus, including absorption spectra, emission spectra, and fluorescence quantum yields are highly similar, leading to negligible changes in the Förster radius with the FRET donor monomeric Teal Fluorescent Protein (mTFP) (1). This substitution thus does not affect the FRET data reported in the original manuscript or their interpretation. The protein mEYFP is based on EYFP (Clontech) with the addition of the mutation A206K to suppress dimerization (2). www.pnas.org/cgi