Department of Biochemistry and Biophysics, University of California, Davis, CA 95616.
Proc Natl Acad Sci U S A. 1989 May;86(10):3469-73. doi: 10.1073/pnas.86.10.3469.
The presence of ATP-dependent, polycation-stimulated protein kinase activity in highly purified phytochrome preparations [Wong, Y.-S., Cheng, H.-C., Walsh, D. A. & Lagarias, J. C. (1986) J. Biol. Chem. 261, 12089-12097] has renewed the hypothesis that the phytochrome photoreceptor possesses enzymatic activity. A prerequisite for protein kinase function is the presence of an ATP binding site. Here we present evidence for a nucleoside triphosphate binding site(s) in the phytochrome molecule. Two ATP analogs, 5'-p-fluorosulfonylbenzoyladenosine and 8-azidoadenosine 5'-triphosphate, were used to affinity label purified Avena phytochrome. Labeling with both reagents is stimulated by the polycations poly(Lys(75),Ala(25)) and histone H1. Coincubation with ATP inhibits the polycation-stimulated labeling of phytochrome. In similar experiments GTP, CTP, UTP, ADP, and pyrophosphate, but not adenosine or AMP, also prevent photoaffinity labeling of phytochrome.
高度纯化的光敏色素制剂中存在依赖于 ATP 的聚阳离子刺激蛋白激酶活性[Wong, Y.-S., Cheng, H.-C., Walsh, D. A. & Lagarias, J. C. (1986) J. Biol. Chem. 261, 12089-12097]，这重新引发了关于光敏色素受体具有酶活性的假说。蛋白激酶功能的一个前提是存在 ATP 结合位点。在这里，我们提出了光敏色素分子中存在核苷三磷酸结合位点（多个）的证据。两种 ATP 类似物，5'-p-氟磺酰基苯甲酰腺苷和 8-叠氮腺苷 5'-三磷酸，被用于亲和标记纯化的燕麦光敏色素。两种试剂的标记均受聚阳离子聚（赖氨酸（75），丙氨酸（25））和组蛋白 H1 的刺激。与 ATP 共孵育可抑制聚阳离子刺激的光敏色素标记。在类似的实验中，GTP、CTP、UTP、ADP 和焦磷酸，但不是腺苷或 AMP，也可防止光敏色素的光亲和标记。
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