deGFP4 is a dual emission, pH-sensitive protein that can be used as a ratiometric pH sensor. deGFP4 is an artificial derivative of the naturally occurring fluorescent protein encoded by the Aequorea victoria GFP gene (UniProtKB:P42212), and contains the mutations C48S, S65T, H148C and T203C (plus a Q80R substitution that arose during cloning) (PMID:12501176).
