DsRed1 is a tetrameric red fluorescent protein with an excitation peak of 558nm and an emission peak of 583nm in vitro. It is an artificial derivative of the naturally occurring fluorescent protein encoded by the Discosoma drFP583 gene (GenBank:AF168419; AAF03369), with the coding region having been optimized for human codon usage. The protein sequence is identical to that of drFP583 except for insertion of a V residue after the start codon (PMID:11753367).