互补决定区
氨基酸
结合位点
生物化学
化学
立体化学
肽序列
生物
基因
分子生物学
作者
Kathleen N. Potter,Paul Hobby,Susanne Klijn,Freda K. Stevenson,Brian J. Sutton
出处
期刊:Journal of Immunology
[The American Association of Immunologists]
日期:2002-10-01
卷期号:169 (7): 3777-3782
被引量:106
标识
DOI:10.4049/jimmunol.169.7.3777
摘要
Abstract The monoclonal IgM cold agglutinins that bind to the I/i carbohydrate Ags on the surface of RBCs all have Ig H chains encoded by the V4-34 gene segment. This mandatory use indicates that distinctive amino acid sequences may be involved in recognition. Critical amino acids exist in framework region 1 (FR1) of V4-34-encoded Ig, and these generate a specific Id determinant which apparently lies close to the I binding site. However, I binding by Id-expressing Ig can be modulated by sequences in complementarity-determining region (CDR)H3. Examination of the crystal structure of an anti-I cold agglutinin has revealed a hydrophobic patch in FR1 involving residue W7 on β-strand A and the AVY motif (residues 23–25) on β-strand B. In this study we used mutagenesis to show that each of the strand components of the hydrophobic patch is required for binding the I carbohydrate Ag. In addition, the crystal structure reveals that amino acids in the carboxyl-terminal region of CDRH3 form a surface region adjacent to the hydrophobic patch. We propose that the I carbohydrate Ag interacts simultaneously with the entire hydrophobic patch in FR1 and with the outside surface of CDRH3. This interaction could leave most of the conventional binding site available for binding other Ags.
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