FIGURE 1:

msYFP2 is a photostable superfolder YFP. (A) Photobleaching of purified YFP variants. The indicated YFPs were imaged repeatedly by widefield microscopy. Images were collected every 0.1 s, and the emission signals were quantified. Each curve was normalized to the emission signal from the first image. (B) Spectra of YFP variants. Purified YFPs were diluted to an absorbance at 280 nm of ∼0.1. Excitation spectra were collected for emission at 527 nm, and emission spectra were collected for excitation at 513 nm. The spectra were normalized to the highest values. (C) Folding stabilities of YFP variants. The indicated YFPs were expressed in E. coli as fusions to proinsulin (“Pro”), and the fluorescence signals from the cells were measured. Plotted in arbitrary units (a.u.) are mean and SEM values from three replicates.