TagRFP-T is a monomeric red fluorescent protein with an excitation peak of 555nm and an emission peak of 584nm in vitro. It is an artificial derivative of the naturally occurring fluorescent protein encoded by the Entacmaea quadricolor eqFP578 gene, derived by mutagenesis of TagRFP, containing the mutation S158T relative to TagRFP. It is approximately nine-fold more photostable than TagRFP (PMID:18454154).