Raghavan M, Wang Y, Bjorkman P J
Division of Biology, California Institute of Technology, Pasadena 91125, USA.
Proc Natl Acad Sci U S A. 1995 Nov 21;92(24):11200-4. doi: 10.1073/pnas.92.24.11200.
The neonatal Fc receptor (FcRn) transports maternal IgG from ingested milk in the gut to the bloodstream of newborn mammals. An FcRn dimer was observed in crystals of the receptor alone and of an FcRn-Fc complex, but its biological relevance was unknown. Here we use surface plasmon resonance-based biosensor assays to assess the role of FcRn dimerization in IgG binding. We find high-affinity IgG binding when FcRn is immobilized on a biosensor chip in an orientation facilitating dimerization but not when its orientation disrupts dimerization. This result supports a model in which IgG-induced dimerization of FcRn is relevant for signaling the cell to initiate endocytosis of the IgG-FcRn complex.
新生儿Fc受体（FcRn）将摄入乳汁中的母体IgG从肠道转运至新生哺乳动物的血液中。在单独的FcRn晶体以及FcRn-Fc复合物晶体中均观察到了FcRn二聚体，但其生物学相关性尚不清楚。在此，我们使用基于表面等离子体共振的生物传感器检测法来评估FcRn二聚化在IgG结合中的作用。我们发现，当FcRn以促进二聚化的方向固定在生物传感器芯片上时，会出现高亲和力的IgG结合，而当它的方向破坏二聚化时则不会出现这种情况。这一结果支持了这样一种模型，即IgG诱导的FcRn二聚化与向细胞发出信号以启动IgG-FcRn复合物的内吞作用有关。
