Binding of mutants of human insulin-like growth factor II to insulin-like growth factor binding proteins 1-6.
Binding of mutants of human insulin-like growth factor II to insulin-like growth factor binding proteins 1-6.
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DOI：
10.1016/s0021-9258(18)98342-0
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发表时间：
1993-05
期刊：
影响因子：
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通讯作者：
Leon A. BachSg;Susan HsiehSfl;Katsu-ichi Sakano;Hiroyuki Fujiwarall;James F. Perdue;Matthew M. RechlerS
中科院分区：
文献类型：
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作者：
Leon A. BachSg;Susan HsiehSfl;Katsu-ichi Sakano;Hiroyuki Fujiwarall;James F. Perdue;Matthew M. RechlerS
一个由6个特异性胰岛素样生长因子结合蛋白（igfbp）组成的家族调节胰岛素样生长因子IGF-I和IGF-II的生物学作用。在本研究中，我们确定了纯化的人igfbp 1-6与重组人IGF-II突变体的结合亲和力，这些突变体与IGF-I、IGF-II/甘露糖6-磷酸和胰岛素受体结合的报道（Sakano， K., Enjoh， T., Numata， F., Fujiwara， H., Marumoto， Y., Higashihashi， N., Sato， Y., Perdue， J. F.和Fujita-Yamaguchi， Y. (1991) J. Biol.）。化学，266,20626-20635)。在研究的区域中，IGF-II与igfbp结合的最重要决定因素是a结构域48-50和b结构域26。用类似于人胰岛素（Thr-Ser-Ile）的残基取代48-50后，与IGFBP-1、-5和-6的结合降低了50倍以上，与IGFBP-4的结合降低了15-50倍；与IGFBP-2和-3的结合减少了6-12倍。同样的取代显著降低了与IGF-II/甘露糖6-磷酸受体的结合，但对IGF-I或胰岛素受体没有影响。虽然用IGF-I （Arg-Arg）的类似残基取代54和55可以消除与IGF-II/甘露糖6-磷酸受体的结合，但与igfbp的结合并未受到实质性影响。用Ser或Leu替代Phe26，减少了与igf -1和胰岛素受体的结合，减少了与IGFBP-1和-6的结合高达80倍，但对其他igfbp的影响较小。与[Ser26]IGF-II相比，[Leu27]IGF-II和[Leu43]IGF-II对IGF-I和胰岛素受体的亲和力明显降低，与IGF-II相比，与IGF-II结合的igfbp的亲和力相对不变。因此，IGF-II与igfbp结合的决定因素部分与IGF-II/甘露糖6-磷酸受体的决定因素重叠，而与IGF-I受体的决定因素重叠程度较小。IGFBP-1和IGFBP-6对IGF-II结构的变化最为敏感，尽管IGFBP-1与IGF-I和IGF-II的结合具有同等的亲和力，而IGFBP-6对IGF-II具有明显的优先结合亲和力。具有特异性igfbp或受体识别选择性损伤的IGF- ii突变体将为剖析不同的IGF结合大分子在调解IGF- ii作用中的作用提供有用的工具。
A family of six specific insulin-like growth factor binding proteins (IGFBPs) modulates the biological actions of the insulin-like growth factors, IGF-I and IGF-II. In the present study, we determined the binding affinity of purified human IGFBPs 1-6 for recombinant human IGF-II mutants whose binding to IGF-I, IGF-II/mannose 6-phosphate, and insulin receptors was previously reported (Sakano, K., Enjoh, T., Numata, F., Fujiwara, H., Marumoto, Y., Higashihashi, N., Sato, Y., Perdue, J. F., and Fujita-Yamaguchi, Y. (1991) J. Biol. Chem. 266, 20626-20635). Of the regions studied, the most important determinants of IGF-II binding to the IGFBPs were A-domain residues 48-50 and B-domain residue 26. Substitution of residues 48-50 with the analogous residues from human insulin (Thr-Ser-Ile) reduced binding to IGFBP-1, -5, and -6 more than 50-fold and to IGFBP-4 by 15-50-fold; binding to IGFBP-2 and -3 was reduced 6-12-fold. The same substitution markedly reduced binding to the IGF-II/mannose 6-phosphate receptor but not to IGF-I or insulin receptors. Although substitution of residues 54 and 55 with the analogous residues from IGF-I (Arg-Arg) abolished binding to the IGF-II/mannose 6-phosphate receptor, binding to IGFBPs was not substantially affected. Substitution of Phe26 with Ser or Leu, which decreased binding to the IGF-I and insulin receptors, reduced binding to IGFBP-1 and -6 up to 80-fold, but had lesser effects on the other IGFBPs. [Leu27]IGF-II and [Leu43]IGF-II, which had a more markedly reduced affinity for the IGF-I and insulin receptors than did [Ser26]IGF-II, were bound by the IGFBPs with relatively unchanged affinity compared with IGF-II. Thus, the determinants of IGF-II binding to IGFBPs partially overlap those for the IGF-II/mannose 6-phosphate receptor and overlap those for the IGF-I receptor to a lesser extent. IGFBP-1 and IGFBP-6 are most sensitive to changes in IGF-II structure, although IGFBP-1 binds IGF-I and IGF-II with equal affinity, whereas IGFBP-6 has a marked preferential binding affinity for IGF-II. IGF-II mutants with selective impairment in recognition by specific IGFBPs or receptors will provide a useful tool for dissecting the role of the different IGF binding macromolecules in the mediation of IGF-II actions.