RT Journal Article SR Electronic T1 Photoactivatable Blue Fluorescent Protein JF bioRxiv FD Cold Spring Harbor Laboratory SP 2023.12.12.571285 DO 10.1101/2023.12.12.571285 A1 Gaytán, Paul A1 Roldán-Salgado, Abigail YR 2024 UL http://biorxiv.org/content/early/2024/03/16/2023.12.12.571285.abstract AB Photoactivable and photoswitchable fluorescent proteins (FPs) are sophisticated molecular tools that in combination with super-resolution microscopy are helping to elucidate many biological processes. Through the Y66H mutation in the chromophore of the violet fluorescent protein sumireF we created the first photoactivatable blue fluorescent protein (PA-BFP). This protein is rapidly activated over ordinary UV transilluminators at 302 nm or 365 nm in irreversible mode. The maximum excitation and emission wavelengths of this protein, centered at 358 nm and 445 nm, respectively, resemble the values of DAPI—the blue stain widely used in fluorescence microscopy to visualize nucleic acids in cells. Therefore, the immediate use of PA-BFP in cellular biology is clear because the technology required to follow this new genetically encoded reporter at the microscopic level has already been established. PA-BFP can potentially be used together with other photoactivatable fluorescent proteins of different colors to label multiple proteins, which can be simultaneously tracked by advanced microscopic techniques.Competing Interest StatementThe authors have declared no competing interest.