GFP(V63A.S65T) is a green fluorescent protein with an excitation peak of 490nm and an emission peak of 510nm in vitro. It is an artificial derivative of the naturally occurring fluorescent protein encoded by the Aequorea victoria GFP gene (UniProtKB:P42212), containing the mutations S56T (PMID:7854443) and V63A (FBrf0229279). GFP(V63A.S65T) is reported to be brighter than GFP(S65T) (FBrf0229279).