Fast-GCaMP-RS06 is a genetically encoded fluorescent Ca[2+] indicator with fast kinetics. It consists of a calmodulin-binding peptide, a circularly permuted green fluorescent protein and calmodulin. Fast-GCaMP-RS06 was derived by mutagenesis of GCaMP3, containing in addition the mutation M374Q (FBrf0222168). For detailed kinetic and spectral properties, see FBrf0222168.