ITODYS, Interactions, Traitements et Organisation des Systèmes, Université Paris-Diderot, CNRS UMR 7086, 15 rue Jean-Antoine de Baïf, 75205, Paris Cedex 13, France.
J Biol Inorg Chem. 2010 May;15(4):497-504. doi: 10.1007/s00775-009-0618-1. Epub 2009 Dec 30.
Transferrin receptor 1 (R(D)) binds iron-loaded transferrin and allows its internalization in the cytoplasm. Human serum transferrin also forms complexes with metals other than iron, including uranium in the uranyl form (UO(2)(2+)). Can the uranyl-saturated transferrin (TUr(2)) follow the receptor-mediated iron-acquisition pathway? In cell-free assays, TUr(2) interacts with R(D) in two different steps. The first is fast, direct rate constant, k(1) = (5.2 +/- 0.8) x 10(6) M(-1) s(-1); reverse rate constant, k(-1) = 95 +/- 5 s(-1); and dissociation constant K(1) = 18 +/- 6 microM. The second occurs in the 100-s range and leads to an increase in the stability of the protein-protein adduct, with an average overall dissociation constant K(d) = 6 +/- 2 microM. This kinetic analysis implies in the proposed in vitro model possible but weak competition between TUr(2) and the C-lobe of iron-loaded transferrin toward the interaction with R(D).
转铁蛋白受体 1（R(D)）结合铁饱和的转铁蛋白并允许其在细胞质中内化。人血清转铁蛋白也与除铁以外的其他金属形成复合物，包括铀酰形式（UO(2)(2+)）的铀。铀酰饱和的转铁蛋白（TUr(2)）是否可以遵循受体介导的铁摄取途径？在无细胞测定中，TUr(2)与 R(D)以两个不同的步骤相互作用。第一个是快速的、直接的速率常数，k(1) = (5.2 +/- 0.8) x 10(6) M(-1) s(-1)；反向速率常数，k(-1) = 95 +/- 5 s(-1)；解离常数 K(1) = 18 +/- 6 microM。第二个发生在 100-s 范围内，导致蛋白-蛋白加合物的稳定性增加，平均总体解离常数 K(d) = 6 +/- 2 microM。这种动力学分析表明，在提出的体外模型中，TUr(2)和铁饱和转铁蛋白的 C 端与 R(D)相互作用之间可能存在但较弱的竞争。
