Genetically encoded calcium indicators (GECIs) are vital tools for fluorescence-based visualization of neuronal activity with high spatial and temporal resolution. However, current highest-performance...

The light response of CarHc protein-based hydrogels can be alterted from photo-weakening, to photo-strengthening, or becoming light-unresponsive depending on the added cofactors AdoCbl and Co2+. Unde....

Pyruvate is the end-product of glycolysis and a central metabolite involved in many biochemical pathways. However, a lack of high-performance (i.e., Δ F / F > 10) single fluorescent protein (FP)-base...

Publishes research papers and review articles relevant to the engineering, design and selection of proteins for use in biotechnology and therapy, and for understanding fundamental properties of activi...

The Japan Society for the Promotion of Science (JSPS) is Japan's leading funding agency and is largely funded through annual subsidies from the Japanese Ministry of Education, Culture, Sports, Science...

Potassium ion (K+) is the most abundant metal ion in cells and plays an indispensable role in practically all biological systems. Although there have been reports of both synthetic and genetically encoded fluorescent K+ indicators, there remains a need for an indicator that is genetically targetable, has high specificity for K+ versus Na+, and has a high fluorescent response in the red to far-red wavelength range. Here, we introduce a series of chemigenetic K+ indicators, designated as the HaloKbp1 series, based on the bacterial K+-binding protein (Kbp) inserted into HaloTag7 self-labeled with environmentally sensitive rhodamine derivatives. This series of high-performance indicators features high brightness in the red to far-red region, large intensiometric fluorescence changes, and a range of Kd values. We demonstrate that they are suitable for the detection of physiologically relevant K+ concentration changes such as those that result from the Ca2+-dependent activation of the BK potassium channel.