It prevents accumulation of the red photoactivated form of orange carotenoid protein (OCP), thereby reducing the amount of fluorescence quenching that occurs between the OCP and the phycobilisome antenna complexes.
[3] Overexpression of FRP in Synechocystis PCC 6803 leads to an absence of fluorescence quenching.
[4] Deletion mutants of FRP show a slightly larger degree of fluorescence quenching induced by strong blue-green light, but was unable to restore fluorescence levels when transferred to low-light or darkness.
Mutations in several other residues within this patch led to poor expression and precipitation, as well as loss of activity.
The FRP gene is transcribed independently from OCP in Synechocystis 6803 and thus the OCP/FRP locus is not considered an operon.