Novel pH- and anion concentration-responsive GFP mutant, a chimeric protein comprising such a mutant and a method for the combined assaying of the pH and anion concentration

摘要

A mutant of the GFP fluorescent protein, designated as D3GFP, is described, the fluorescence of which is sensitive to both the pH and anion concentration. A chimeric protein comprising a first protein, P1, and a second protein, P2, is further described, wherein the P1 protein is a fluorescent protein sensitive to the pH and anion concentration - such as the D3GFP mutant - and the P2 protein is a fluorescent protein, the fluorescence of which is independent from both the pH and anion concentration. In addition, P2 is selected so that there is no substantial overlapping of the P1 and P2 emission and excitation fluorescence spectra. A method is also described for the combined measurement of the pH and anion concentration (for instance the intracellular chlorine ions) by using the said chimeric protein.