Albumin binding to FcRn: Distinct from the FcRn-IgG interaction
Albumin binding to FcRn: Distinct from the FcRn-IgG interaction
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DOI：
10.1021/bi052628y
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发表时间：
2006-04-18
期刊：
影响因子：
2.9
通讯作者：
Anderson, CL
中科院分区：
文献类型：
--
作者：
Chaudhury, C;Brooks, CL;Anderson, CL
MHC相关的免疫球蛋白Fc受体(FcRN)通过在低pH值下与酸性内吞体内高亲和力的蛋白结合，并将两者从溶酶体途径转移到细胞外，从而保护白蛋白和免疫球蛋白免于降解。免疫印迹和表面等离子体共振研究表明，免疫球蛋白和白蛋白都非协同地结合到FcRN上的不同位置，从酸性到中性，FcRN与白蛋白的亲和力下降了近200倍，FcRN与白蛋白的相互作用表现出快速的结合和解离动力学。等温滴定量热法表明，白蛋白与FcRN以1：1的化学计量比结合，结合时结合时的熵有很大的正变化，表明这种相互作用具有疏水性。我们的结果表明，FcRN-白蛋白相互作用具有不同于FcRN-IgG结合的独特特征，尽管两种配体的pH依赖结合机制总体上相似，通过这种结合机制两种配体都不会被降解。
The MHC-related Fc receptor for IgG (FcRn) protects albumin and IgG from degradation by binding both proteins with high affinity at low pH in the acid endosome and diverting both from a lysosomal pathway, returning them to the extracellular compartment. Immunoblotting and surface plasmon resonance studies show that both IgG and albumin bind noncooperatively to distinct sites on FcRn, that the affinity of FcRn for albumin decreases approximate to 200-fold from acidic to neutral pH, and that the FcRn-albumin interaction shows rapid association and dissociation kinetics. Isothermal titration calorimetry shows that albumin binds FcRn with a 1: 1 stoichiometry and the interaction has hydrophobic features as evidenced by a large positive change in entropy upon binding. Our results suggest that the FcRn-albumin interaction has unique features distinct from FcRn-IgG binding despite the overall similarity in the pH-dependent binding mechanism by which both ligands are protected from degradation.