Takei Y, Takahashi K, Kanaho Y, Katada T
Department of Life Science, Tokyo Institute of Technology, Yokohama, Japan.
FEBS Lett. 1994 Feb 7;338(3):264-6. doi: 10.1016/0014-5793(94)80280-7.
ADP-ribose moiety containing digoxigenin was transferred by pertussis toxin (IAP) to the alpha subunit of Gi (Gi alpha) from digoxigenin-conjugated NAD (DIG-NAD) in a beta gamma subunit-dependent manner. ADP-ribosylation of Gi alpha with DIG-NAD plus IAP was inhibited by native NAD. These results indicate that non-radiolabeled DIG-NAD also serves as the substrate for IAP-catalyzed ADP-ribosylation of G proteins. Using DIG-NAD and fluorescein isothiocyanate-labeled anti-digoxigenin antibody, IAP-sensitive G protein(s) was found to be exist in nuclei as well as plasma membranes of rat liver and HeLa cells. Thus, DIG-NAD is useful to identify pertussis toxin-substrate G proteins.
含地高辛配基的ADP-核糖部分由百日咳毒素（IAP）以βγ亚基依赖的方式从地高辛配基结合的NAD（DIG-NAD）转移至Gi的α亚基（Giα）。天然NAD抑制了用DIG-NAD加IAP对Giα进行的ADP-核糖基化。这些结果表明，非放射性标记的DIG-NAD也可用作IAP催化的G蛋白ADP-核糖基化的底物。利用DIG-NAD和异硫氰酸荧光素标记的抗地高辛配基抗体，发现IAP敏感的G蛋白存在于大鼠肝脏和HeLa细胞的细胞核以及质膜中。因此，DIG-NAD对于鉴定百日咳毒素底物G蛋白很有用。
