DsRed(T3) is a tetrameric red fluorescent protein with an excitation peak of 560nm and an emission peak of 587nm in vitro. It is a fast-maturing artificial derivative of the naturally occurring fluorescent protein encoded by the Discosoma drFP583 gene (GenBank:AF168419; AAF03369), containing the mutations P(-4)L (this represents a codon change in the polylinker upstream of the start codon), R2A, K5E, N6D, T21S, H41T, N42Q, V44A and A145P relative to drFP583. In addition, the open-reading frame has been optimized for mammalian codon usage (PMID:11753367).