Miyashita Y, Moriya T, Yokosawa N, Hatta S, Arai J, Kusunoki S, Toratani S, Yokosawa H, Fujii N, Asami K
Department of Biology, Faculty of Medicine, Sapporo Medical University, Japan.
J Exp Zool. 1996 Oct 1;276(2):125-31. doi: 10.1002/(SICI)1097-010X(19961001)276:2<125::AID-JEZ5>3.0.CO;2-Q.
Melanophores of the isolated tail fin of the Xenopus tadpole aggregate melanin granules in response to light. This aggregation was found to be inhibited by subcutaneous injection of exoenzyme C3 of Clostridium botulinum. A 26 kDa protein in homogenate obtained from the Xenopus tail fin was ADP-ribosylated by exoenzyme C3. This reaction was inhibited effectively by a monoclonal antibody, anti-Rho mab A5. raised against the small GTP-binding protein Rho. The extent of ADP-ribosylation depended on light and guanine nucleotide. Incubation under illumination partly reduced ADP-ribosylation and the reduction was restored by addition of guanine nucleotide during incubation. These findings suggest that Rho is involved in the photo-sensitive melanophore response as a signal transducer linking photo-stimuli to melanin granule translocation with Xenopus melanophores.
非洲爪蟾蝌蚪分离出的尾鳍中的黑素细胞会根据光刺激聚集黑色素颗粒。研究发现，皮下注射肉毒杆菌外毒素C3可抑制这种聚集。从非洲爪蟾尾鳍匀浆中获得的一种26 kDa蛋白质被外毒素C3进行了ADP核糖基化修饰。针对小GTP结合蛋白Rho产生的单克隆抗体抗Rho mab A5可有效抑制该反应。ADP核糖基化的程度取决于光和鸟嘌呤核苷酸。光照下孵育会部分降低ADP核糖基化程度，孵育期间添加鸟嘌呤核苷酸可恢复这种降低。这些发现表明，Rho作为一种信号转导分子，参与了非洲爪蟾黑素细胞中光刺激与黑色素颗粒转运之间的光敏反应。
