Domain structure of human α2‐macroglobulin

FEBS Letters

Sottrup-Jensen, Lars¹  Gliemann, Jørgen¹  Van Leuven, Fred¹ 

[1] Department of Molecular Biology, University of Aarhus, DK-8000 Aarhus C, Denmark

关键词: α2-Macroglobulin;    Domain structure;    Proteolysis;    Papain;    Cellular receptor;    Chemical modification;    α2M;    α2-macroglobulin (human);    α2M· MA;    α2-macroglobulin treated with CH3NH2 and ICH2CONH2;    EDC;    ethyldimethylaminopropyl carbodiimide;    DTT;    dithiothreitol;    GuHCl;    guanidinium chloride;    α2MT;    α2-macroglobulin-trypsin complex;   

DOI  :  10.1016/0014-5793(86)80857-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Digestion of methylamine-treated α₂-macroglobulin (α₂M·MA) with catalytic amounts of papain at pH 4.5 has been investigated. Cleavage of Lys(1313)-Glu resulted in two major products, which could be separated by gel chromatograhy: a large disulfide bridged fragment set nearly the size of intact α₂M·MA, and an 18 kDa fragment, constituting the carboxy-terminal domain of α₂M. This domain contained the receptor recognition site, exposed as a result of cleavage of the internal β-cysteinyl-γ-glutamyl thiol esters in α₂M. Compared with α₂M-trypsin complex the apparent affinity for binding to rat hepatocyte receptors was 0.1 and 2% at 4 and 37°C, respectively. The receptor-binding domain presumably forms a compact globular β-barrel-type structure, stable at pH 2.5–9.0. Chemical modification experiments suggest that receptor binding is contributed by a determinant formed by the precise folding of the polypeptide chain.

【 授权许可】

Unknown