Plant Biology Department, The University, Newcastle upon Tyne, NE1 7RU, England.
Plant Physiol. 1979 Mar;63(3):503-6. doi: 10.1104/pp.63.3.503.
Red light given to dark-grown etiolated leaves of Hordeum vulgare L. in vivo or to crude homogenates increases the phytochrome content of the 20,000 g pellet on centrifugation. The steroids cholesterol and stigmasterol inhibit this red light-induced phytochrome pelletability. Filipin (a polyene antibiotic, which is known to combine with steroids) inhibits red light-induced phytochrome pelletability. Filipin and steroids at the appropriate concentration applied together prevent the inhibition caused by either when applied alone. These results suggest that phytochrome may bind to a steroid component of membranes. The phospholipid phosphatidyl choline dipalmitoyl has no effect on red light-induced phytochrome pelletability. Preliminary evidence demonstrates a direct association of soluble phytochrome in its active form and steroids. The physiological significance of red light-induced pelletability and the primary mechanism of phytochrome action are discussed in terms of a hypothetical steroid-binding site.
活体条件下用红光照射黑暗中生长的大麦黄化叶片，或照射粗匀浆，可增加 20,000g 离心沉淀中的光敏素含量。固醇类中的胆固醇和豆固醇抑制这种红光诱导的光敏素沉淀能力。菲啶（一种多烯抗生素，已知与固醇结合）抑制红光诱导的光敏素沉淀能力。当两者以适当浓度共同使用时，可防止单独使用任一药物引起的抑制。这些结果表明，光敏素可能与膜的固醇成分结合。磷脂酰胆碱二棕榈酸对红光诱导的光敏素沉淀能力没有影响。初步证据表明，活性形式的可溶性光敏素与固醇直接相关。根据假设的固醇结合部位，讨论了红光诱导的沉淀能力和光敏素作用的主要机制的生理意义。
