Biliproteins: versatile fluorescent, photochromic and radiationless molecular probes

Summary form only given. Biliproteins represent a diverse class of highly pigmented proteins that utilize light energy throughout the visible and near infrared (NIR) region of the light spectrum. Consisting of two parts, an (apo)protein and a linear tetrapyrrole (bilin) pigment, biliproteins harvest light energy for transfer to the photosynthetic apparatus of photosynthetic bacteria with high quantum efficiencies (i.e. ycobiliproteins), act as sensors of the light environment by perceiving light quality, quantity, direction and duration (i.e. phytochromes) and function as regulators of tetrapyrrole biosynthesis and/or iron homeostasis (i.e. bacteriophytochromes).