text: Upon illumination with blue-green light, OCP switches from an orange form (OCP) to a red form (OCP). The reversion of OCP to OCP is light independent and occurs slowly in darkness. OCP is considered the dark, stable form of the protein, and does not contribute to phycobilisome quenching.  OCP is considered to be essential for induction of the photoprotection mechanism.  The photoconversion from the orange to red form has a poor light efficiency (very low quantum yield), which helps to ensure the protein's photoprotective role only functions during high light conditions;  otherwise, the dissipative NPQ process could unproductively divert light energy away from photosynthesis under light-limiting conditions.