Staphylococcal Protein A and Human IgG Subclasses and Allotypes |
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| Authors: | E. VAN LOGHEM B. FRANGIONE B. RECHT E. C. FRANKLIN |
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| Affiliation: | Central Laboratory of the Netherlands Red Cross Blood Transfusion Service and Laboratory for Experimental and Clinical Immunology, University of Amsterdam, Amsterdam, The Netherlands, and New York University Medical Center, New York, New York, USA |
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| Abstract: | ![]()
Staphylocoecal protein A binds molecules belonging to the IgGl, IgG2, and IgG4 sub-classes. IgG3 proteins generally do not bind, except for those coded by the two γ3 alleles, which are G3m(u−): G3m(b0,b3,b5,s,v) and G3m(b0,b3,b5,s,t,v). G3m(u) is located in the CH2 domain. The difference between G3m(u−) and G3m(u+) IgG3 proteins correlates with the sequence at position 339 in the CH2 domain—Ala and Thr respectively. There is another structural difference in the CH3 domain which correlates with protein A binding and non-binding: all IgG proteins that bind protein A have His at position 435, whereas those that do not, have Arg at that position. |
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