Human IgG2 can form covalent dimers.
Unlike IgA and IgM, IgG has not yet been shown to form covalent polymers. However in the presence of specific Ag, murine IgG3 has been shown to polymerize through noncovalent interactions. In contrast to the noncovalent oligomers found with murine IgG3, we have detected covalent dimers in three different recombinant human IgG2 Abs produced in myeloma cells. Both IgG2,kappa and IgG2,lambda can form dimers. In addition, analysis of pooled human gamma globulin and several normal sera revealed the presence of IgG2 dimers. The IgG2 dimers are in contrast to the noncovalent IgG dimers found in pooled sera of multiple donors resulting from idiotype/anti-idiotype (Id/anti-Id) interactions. Cyanogen bromide cleavage analysis suggests that one or more Cys residues in the gamma 2 hinge are involved in dimer assembly. The potential role of IgG2 dimers in immunity against carbohydrate Ags is discussed.
Yoo
Esther M
EM
Department of Microbiology, Immunology, and Molecular Genetics and Molecular Biology Institute, University of California, Los Angeles, CA 90095,USA.
Wims
Letitia A
LA
Chan
Lisa A
LA
Morrison
Sherie L
SL
D000595:Amino Acid Sequence; D000818:Animals; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D019281:Dimerization; D006801:Humans; D007106:Immune Sera / Q000032:analysis; D007127:Immunoglobulin Constant Regions / Q000032:analysis / Q000235:genetics; D007074:Immunoglobulin G / Q000032:analysis / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D007143:Immunoglobulin Heavy Chains / Q000032:analysis / Q000378:metabolism; D007147:Immunoglobulin Light Chains / Q000032:analysis / Q000378:metabolism; D007135:Immunoglobulin Variable Region / Q000032:analysis / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000378:metabolism
D007106:Immune Sera; D007127:Immunoglobulin Constant Regions; D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D011993:Recombinant Fusion Proteins; D003545:Cysteine