RESIDUES 484-508 CONTAIN A MAJOR DETERMINANT OF THE INHIBITORY EPITOPE IN THE A2 DOMAIN OF HUMAN FACTOR-VIII

被引:125
作者
HEALEY, JF
LUBIN, IM
NAKAI, H
SAENKO, EL
HOYER, LW
SCANDELLA, D
LOLLAR, P
机构
[1] EMORY UNIV,ATLANTA,GA 30322
[2] AMER RED CROSS,HOLLAND LAB,ROCKVILLE,MD 20855
关键词
D O I
10.1074/jbc.270.24.14505
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The A2 domain (residues 373-740) of human blood coagulation factor VIII (fVIII) contains a major epitope for inhibitory alloantibodies and autoantibodies. We took advantage of the differential reactivity of inhibitory antibodies with human and porcine fVIII and mapped a major determinant of the A2 epitope by using a series; of active recombinant hybrid human/porcine fVIII molecules. Hybrids containing a substitution of porcine sequence at segment 410-508, 445-508, or 484-508 of the human A2 domain were not inhibited by a murine monoclonal antibody A2 inhibitor, mAb 413, whereas hybrids containing substitutions at 387-403, 387-444, and 387-468 were inhibited by mAb 413, This indicates that the segment bounded by Arg(484) and Ile(508) contains a major determinant of the A2 epitope. mAb 413 did not inhibit two more hybrids that contained porcine substitutions at residues 484-488 and 489-508, indicating that amino acid side chains on both sides of the Ser(488)-Arg(489) band within the Arg(484)-Ile(508) segment contribute to the A2 epitope. The 484-508, 484-488, and 489-508 porcine substitution hybrids displayed decreased inhibition by A2 inhibitors from four patient plasmas, suggesting that there is little variation in the structure of the A2 epitope in the inhibitor population.
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页码:14505 / 14509
页数:5
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