PATagRFP is a monomeric photoactivatable fluorescent protein. It is irreversibly converted from a dark state to a red fluorescent protein upon irradiation with a pulse of light of peak activation wavelength 400-420nm. The red fluorescent form has an excitation peak of 562nm and an emission peak of 595nm. PATagRFP was derived by mutagenesis of TagRFP, containing the amino acid substitutions R69S, F84W, Q139K, A147P, N148S, M151K, Y153K, S165V, H203R, R207I, V218W and C229S relative to TagRFP (PMID:20394363).