Phycobiliproteins

Literature References: Deeply colored, highly fluorescent photoreceptor pigments found in blue-green, red and cryptomonad algae that contain a linear tetrapyrrole as the prosthetic group. They are composed of a bile pigment or phycobilin and an apoprotein. Phycobiliproteins are classified according to uv-vis absorption maxima as phycocyanins (blue pigment), phycoerythrins (red pigment), and allophycocyanins (pale blue pigment). Phycocyanins and phycoerythrins occur as large mol wt aggregates called phycobilisomes that are attached to the photosynthetic membranes. They are closely linked to the chlorophyll containing system for efficient energy transfer. Phytochrome is a similar biliprotein that functions in plant photomorphogenesis. It is widely distributed in plants but only in trace amounts. It exists in two forms that are interconverted upon alternate exposure to red and far-red light. Reviews: H. W. Siegelman et al., Biochem. Soc. Symp. 28, 107-120 (1968); P. O'Carra, C. O'hEocha in Chemistry and Biochemistry of Plant Pigments vol. 1, T. W. Goodwin, Ed. (Academic, New York, 2nd ed., 1976) pp 328-376; A. Bennett, H. W. Siegelman in Porphyrins vol. 6, D. Dolphin, Ed. (Academic, New York, 1979) pp 493-520.