Td. Pack et al., IDENTIFICATION OF 2 FUNCTIONAL FORMS OF IMMUNOGLOBULIN G3-BINDING PROTEIN EXPRESSED BY GROUP-A STREPTOCOCCI, Infection and immunity, 62(5), 1994, pp. 2104-2107
Analysis of group A streptococcal immunoglobulin G (IgG)-binding prote
in reactivity with different human IgG3-myeloma proteins provided evid
ence for at least two functional forms of these molecules. Representat
ive IgG3-binding molecules were isolated, bitinylated, and used as tra
cers in competitive binding assays. Cross-inhibition studies demonstra
ted the existence of two distinct patterns of IgG3-binding activity. P
roteins of one form could be inhibited from binding to an IgG3-myeloma
protein by streptococcal protein G while binding of the second form w
as not inhibited. These studies further underscore the extent of heter
ogeneity among immunoglobulin-binding proteins expressed by group A st
reptococci.