PyronicSF is a genetically encoded fluorescent sensor for pyruvate. It consists of the full-length pdhR gene from Escherichia coli (this gene encodes a transcriptional regulator that controls the expression of the pyruvate dehydrogenase gene in response to pyruvate) into which a circularly-permuted version of GFP has been inserted (in between pdhR amino acid residues 188 and 189). Upon excitation by blue light, exposure to pyruvate results in a strong increase in fluorescence (when excited at 488nm, the increase in fluorescence emission is approximately 250%) (FBrf0245209).