ECFP is a monomeric cyan fluorescent protein (PMID:20664080). It has a major excitation peak of 434nm (minor peak at 452nm) with an emission peak of 476nm (minor peak at 505nm) in vitro (PMID:9759496). It is an artificial derivative of the naturally occurring fluorescent protein encoded by the Aequorea victoria GFP gene (UniProtKB:P42212), containing the mutations F64L, S65T, Y66W, N146I, M153T and V163A (PMID:9759496).