A key amino acid determining G3m(b) allotypic markers.
A key amino acid substitution specific for allotypic Gm b markers, b0, b3, b5, were determined through sequence analyses of the pFc' fragments of IgG1 (Su) and IgG3 (Ba[Gm(g)], Bu[Gm(b1b3)], and Kam[Gm(b3st)]) myeloma proteins. The results indicate that serine at position 384 is responsible for the specificities. It is considered from crystallographic data of IgG-Fc [Deisenhofer et al. (1981) Biochemistry 20:2361] that two residues, the serine and isoleucine specific for IgG3 subclass at position 422, cause the structural change responsible for b markers. The two residues are close to each other in the CH3 domain. The allocations of the epitopes are estimated to be on two bends (residue no. 382-392, 411-424) between the beta-strands, whose amino acid residues are present in wide contact area [Novotny et al. (1987) Immunol. Today 8:26).
Ito
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Department of Legal Medicine, Osaka Medical College, Japan.
Suzuki
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Miyazaki
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Matsumoto
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D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D000939:Epitopes / Q000737:chemistry; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000737:chemistry*; D007074:Immunoglobulin G / Q000737:chemistry*; D007129:Immunoglobulin Gm Allotypes / Q000737:chemistry*; D008239:Lysine / Q000378:metabolism; D008745:Methylation; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012694:Serine / Q000737:chemistry*
D000596:Amino Acids; D000939:Epitopes; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007129:Immunoglobulin Gm Allotypes; D012694:Serine; D008239:Lysine