Terashima M, Yamamori C, Shimoyama M, Tsuchiya M
Department of Biochemistry, Shimane Medical University, Izumo 693-8501, Japan.
Biochim Biophys Acta. 1998 Sep 16;1404(3):299-304. doi: 10.1016/s0167-4889(98)00067-6.
Arginine-specific ADP-ribosyltransferase present in secretory granules of chicken polymorphonuclear leukocytes (so-called heterophils) was shown to be released into the extracellular space by secretagogues (Terashima et al., J. Biochem. 120 (1996) 1209-1215). In the present work, we examined fibronectin as an extracellular target protein of the released transferase. Fibronectin was ADP-ribosylated by purified transferase and stoichiometry of ADP-ribose incorporation into fibronectin was 1.0 mol/mol of fibronectin. Cell adhesion and spreading assays revealed that ADP-ribosylation of fibronectin markedly inhibited the adhesion activity of fibronectin. A proteolytic peptide map of ADP-ribosylated fibronectin demonstrated that the modification occurs in the cell binding domain of fibronectin. ADP-ribosylation of the RGD peptide suggests that the RGD sequence is the modification site in the domain. ADP-ribosylation of fibronectin in plasma means that fibronectin can probably serve as the substrate for extracellularly released ADP-ribosyltransferase in vivo. Thus, in the extracellular space, ADP-ribosyltransferase released from polymorphonuclear leukocytes may perhaps be involved in regulation of cell adhesion process by interfering with the activity of fibronectin.
存在于鸡多形核白细胞（所谓的异嗜细胞）分泌颗粒中的精氨酸特异性ADP-核糖基转移酶已被证明可被促分泌剂释放到细胞外空间（寺岛等人，《生物化学杂志》120（1996）1209 - 1215）。在本研究中，我们检测了纤连蛋白作为释放的转移酶的细胞外靶蛋白。纯化的转移酶可使纤连蛋白发生ADP-核糖基化，并且ADP-核糖掺入纤连蛋白的化学计量比为每摩尔纤连蛋白1.0摩尔。细胞黏附和铺展试验表明，纤连蛋白的ADP-核糖基化显著抑制了纤连蛋白的黏附活性。ADP-核糖基化纤连蛋白的蛋白水解肽图谱显示，修饰发生在纤连蛋白的细胞结合结构域。RGD肽的ADP-核糖基化表明RGD序列是该结构域中的修饰位点。血浆中纤连蛋白的ADP-核糖基化意味着纤连蛋白在体内可能作为细胞外释放的ADP-核糖基转移酶的底物。因此，在细胞外空间，多形核白细胞释放的ADP-核糖基转移酶可能通过干扰纤连蛋白的活性参与细胞黏附过程的调节。
