Identification and biochemical characterization of a novel receptor:ligand interaction between FcRn and albumin.

摘要

The inverse relationship between serum albumin concentration and its half-life suggested to early workers that albumin would be protected from a catabolic fate by a receptor mediated mechanism much like that proposed for IgG. This work shows that albumin binds FcRn in a pH dependent fashion, that the lifespan of albumin is shortened in FcRn-deficient mice, and that the plasma albumin concentration of FcRn-deficient mice is less than half that of wild type mice. This study further characterizes the molecular interaction of albumin with FcRn by determining affinity, kinetic rate constants, stoichiometry of interaction and the effect of IgG on the interaction. This study employs western blot analysis, ELISA, animal studies, surface plasmon resonance and isothermal titration calorimetry as experimental tools for these analyses. These results affirm the hypothesis that the MHC-related Fc receptor protects albumin from degradation just as it does IgG, prolonging the half-lives of both.