Delbé J, Blat C, Desauty G, Harel L
Institut de Recherches Scientifiques sur le Cancer, Villejuif, France.
Biochem Biophys Res Commun. 1991 Aug 30;179(1):495-501. doi: 10.1016/0006-291x(91)91398-v.
IDF45 (inhibitory diffusible factor) a mouse insulin-like growth factor binding protein (mlGFBP-3) has been shown to 100 percent inhibit DNA synthesis stimulated by serum in chick embryo fibroblasts (CEF). Our previous results suggested that this large inhibition by IDF45 of serum stimulation was not just the result of its inhibitory activity toward IGF present in serum. The addition of Mn2+ (10(-3)M) in the incubation medium enables us to show the presence of numerous binding sites per cells (about 60,000) of mlGFBP-3. However the dissociation constant (10(-8)M) indicated that this mouse IGFBP-3 bound to the membrane with low affinity. These findings lend new support to the assumption of the bifunctional property of IGFBP-3, which would have an effect outside the cell (binding of IGF in the medium) and another effect within cells or on the surface.
IDF45（抑制性扩散因子），一种小鼠胰岛素样生长因子结合蛋白（mlGFBP - 3），已被证明能100%抑制鸡胚成纤维细胞（CEF）中由血清刺激的DNA合成。我们之前的结果表明，IDF45对血清刺激的这种强烈抑制不仅仅是其对血清中存在的IGF抑制活性的结果。在孵育培养基中添加Mn2 +（10^(-3)M）使我们能够显示每个细胞存在大量mlGFBP - 3的结合位点（约60,000个）。然而，解离常数（10^(-8)M）表明这种小鼠IGFBP - 3与膜的结合亲和力较低。这些发现为IGFBP - 3具有双功能特性的假设提供了新的支持，即它在细胞外（结合培养基中的IGF）和细胞内或细胞表面具有不同的作用。
