Crystal structure of the receptor-binding domain of α2-macroglobulin

Background: The large plasma proteinase inhibitors of the α2-macroglobulin superfamily inhibit proteinases by capturing them within a central cavity of the inhibitor molecule. After reaction with the proteinase, the α-macroglobulin–proteinase complex binds to the α-macroglobulin receptor, present in the liver and other tissues, and becomes endocytosed and rapidly removed from the circulation. The complex binds to the receptor via recognition...