Kojima S, Inui T, Muramatsu H, Suzuki Y, Kadomatsu K, Yoshizawa M, Hirose S, Kimura T, Sakakibara S, Muramatsu T
Laboratory of Gene Technology and Safety, Tsukuba Life Science Center, The Institute of Physical and Chemical Research (RIKEN), Koyadai, Tsukuba, Ibaraki 305, Japan.
J Biol Chem. 1997 Apr 4;272(14):9410-6. doi: 10.1074/jbc.272.14.9410.
Midkine (MK), a retinoic acid-inducible growth/differentiation factor, serves as a substrate for tissue transglutaminase (Kojima, S. , Muramatsu, H., Amanuma, H., and Muramatsu, T. 1995. J. Biol. Chem. 270, 9590-9596). Upon incubation with transglutaminase MK forms multimers through cross-linkages. Here, we report the following results. 1) Heparin potentiated the multimer formation by MK. 2) The N- and C-terminal half domains each formed a dimer through the action of transglutaminase. 3) Gln42 or Gln44 in the N-terminal half and Gln95 in the C-terminal half served as amine acceptors in the cross-linking reaction, as judged from the incorporation of putrescine into whole MK or each half domain, and the competitive inhibition of the cross-linking by MK-derived peptides containing Gln residue(s). The strongest inhibition was obtained with Ala41-Pro51. 4) This peptide abolished the biological activity of MK to enhance the plasminogen activator activity in bovine aortic endothelial cells. The inhibition was limited against the MK monomer, and not seen against the MK dimer, separated by gel filtration chromatography. These results suggest that dimer formation through transglutaminase-mediated cross-linking is an important step as to the biological activity of MK.
中期因子（MK）是一种视黄酸诱导的生长/分化因子，可作为组织转谷氨酰胺酶的底物（小岛，S.，村松，H.，天沼，H.，和村松，T. 1995.《生物化学杂志》270，9590 - 9596）。与转谷氨酰胺酶一起孵育时，MK通过交联形成多聚体。在此，我们报告以下结果。1）肝素增强了MK介导的多聚体形成。2）N端和C端半结构域各自通过转谷氨酰胺酶的作用形成二聚体。3）从腐胺掺入完整的MK或每个半结构域以及含Gln残基的MK衍生肽对交联的竞争性抑制判断，N端半结构域中的Gln42或Gln44以及C端半结构域中的Gln95在交联反应中作为胺受体。用Ala41 - Pro51获得的抑制作用最强。4）该肽消除了MK增强牛主动脉内皮细胞中纤溶酶原激活剂活性的生物学活性。这种抑制作用对MK单体有限，而对通过凝胶过滤色谱分离的MK二聚体未见抑制作用。这些结果表明，通过转谷氨酰胺酶介导的交联形成二聚体是MK生物学活性的重要步骤。
