光受容タンパク質・ロドプシンの生物物理化学研究

Opsins (also called animal rhodopsins) are universal photoreceptive proteins that provide the molecular basis of visual and nonvisual photoreception in animals, including humans. Opsins consist of seven helical a-transmembrane domains and use retinal, a derivative of vitamin A, as a chromophore. In many opsins, light absorption triggers photoisomerization from 11-cis retinal to all-trans retinal, resulting in activation via dynamic structural changes in the protein moiety. Activated opsins stimulate cognate trimeric G proteins to induce signal transduction cascades in cells. Recently, molecular and physiological analyses of diverse opsins have progressively advanced. This review introduces the molecu¬ lar basis and physiological functions of opsins. Based on the functions of opsins, I will discuss the potential of opsins as target molecules to treat and prevent visual and nonvisual diseases such as sleep disorder and depression.