1edy
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CRYSTAL STRUCTURE OF RAT ALPHA 1-MACROGLOBULIN RECEPTOR BINDING DOMAIN
OverviewOverview
Alpha-macroglobulin inhibits a broad spectrum of proteinases by forming, macromolecular cages inside which proteinases are cross-linked and, trapped. Upon formation of a complex with proteinase, alpha-macroglobulin, undergoes a large conformational change that results in the exposure of, its receptor-binding domain (RBD). Engagement of this domain by, alpha-macroglobulin receptor permits clearance of the alpha-macroglobulin:, proteinase complex from circulation. The crystal structure of rat, alpha1-macroglobulin RBD has been determined at 2.3 A resolution. The RBD, is composed of a nine-stranded beta-sandwich and a single alpha-helix that, has been implicated as part of the receptor binding site and that lies on, the surface of the beta-sandwich. The crystallographic asymmetric unit, contains a dimer of RBDs related by approximate twofold symmetry such that, the putative receptor recognition sites of the two monomers are, contiguous. By gel filtration and ultracentrifugation, it is shown that, RBD dimers form in solution with a dissociation constant of approximately, 50 microM. The structure of the RBD dimer might mimic a conformation of, transformed alpha-macroglobulin in which the proposed receptor binding, residues are exposed on one face of the dimer. A pair of phenylalanine, residues replaces a cystine that is conserved in other members of the, macroglobulin family. These residues participate in a network of aromatic, side-chain interactions that appears to stabilize the dimer interface.
About this StructureAbout this Structure
1EDY is a Single protein structure of sequence from Rattus norvegicus. Full crystallographic information is available from OCA.
ReferenceReference
Structure of a rat alpha 1-macroglobulin receptor-binding domain dimer., Xiao T, DeCamp DL, Spran SR, Protein Sci. 2000 Oct;9(10):1889-97. PMID:11106161
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