|State||Ex λ||Em λ||EC (M-1 cm-1)||QY||Brightness||pKa||Maturation (min)||Lifetime (ns)|
no photostability measurements available ... add one!
Single pcFP counting in individual bacterial cells by PALM/STORM reveals that a key contributor to the favorable properties of mMaple is a high intracellular concentration of properly folded (and therefore photoconvertible) mMaple fusion proteins.
When the brightness of a large population of cells was assessed by flow cytometry, it was apparent that mMaple-actin or mMaple-actinin was not brighter than either of the corresponding mEos2 or mClavGR2 fusions when expressed in mammalian cells. For the actinin fusion, mClavGR2 had the greatest fraction of bright cells, followed by mMaple and mEos2. For the actin fusion, mClavGR2 and mEos2 had similar distributions that were shifted towards higher brightness relative to mMaple... Although these results were disappointing, we noted that the photostability of mMaple-actin is improved by almost three-fold, increasing the utility of the mMaple-actin construct in applications requiring green-state photostability.
... we compared the relative signaling efficiency of different PAFPs by determining the number of single-molecule localizations per cell of the PAFPs fused to a common target protein under endogenous expression. We fused the PAFPs to the E. coli gene hupA, which encodes a subunit of the nucleoid-associated protein HU, at its endogenous chromosomal locus and determined the total number of HU-PAFP localizations per cell. Among the red PAFPs, mMaple provided by far the largest number of HU localizations, which was 6- to 32-fold higher than those of other HU-PAFP fusion proteins.
We first took inspiration from the two mutations that make mEos3.2 more monomeric than mEos2: I102N and Y189A (15). Based on a sequence alignment between mEos2 and mMaple, we made the comparable mutations, I111N and Y198A, in mMaple... mMaple2 exhibited a similar photon budget, on–off ratio, and signaling efficiency as those of mMaple. ClpP-mMaple2 proteins still formed puncta in some cells. However, the percentage of cells showing single punctum was significantly reduced in comparison with ClpP-mMaple, suggesting a lower dimerization tendency of mMaple2.