[Interaction of thyroid hormones with immunoglobulins isolated from human blood serum. II. Structural elements and localization of thyroxine-binding segment in the immunoglobulin M molecule].
The structural characteristics and topography of the thyroxine T4-binding site on the human immunoglobulin M (IgM) molecule have been studied using affinity binding with T4 structural analogs blocking the formation of the T4-IgM complex with proteins displaying an affinity for individual structural components of IgM and proteolytic fragmentation followed by determination of the T4-binding activity of the isolated fragments. It has been found that IgM has a poor selectivity towards the binding of T4 structural analogs which is characteristic of transport proteins but not of autoantibodies. The T4-binding region of IgM lies outside the variable portion of the Fab-fragment and is apparently constituted by the Cmu 1-domain of the heavy chain and the constant part of the light chain linked via a disulphide bridge. The T4-binding site located within this region possesses no stereospecificity and contains structural elements complementary to the iodine atoms of the outer ring and the aliphatic chain of the iodothyronine molecule.
Ermolenko
M N
MN
Sviridov
O V
OV
D001665:Binding Sites; D006801:Humans; D006868:Hydrolysis; D007075:Immunoglobulin M / Q000097:blood / Q000378:metabolism*; D013974:Thyroxine / Q000378:metabolism*
D007075:Immunoglobulin M; D013974:Thyroxine
Vzaimodeĭstvie tiroidnykh gormonov s immunoglobulinami, vydelennymi iz syvorotki krovi cheloveka. II. Strukturnye élementy i lokalizatsiia tiroksinsviazyvaiushchego uchastka v molekule immunoglobulina M.