title: Identification of two functional forms of immunoglobulin G3-binding protein expressed by group A streptococci.
abstract: Analysis of group A streptococcal immunoglobulin G (IgG)-binding protein reactivity with different human IgG3-myeloma proteins provided evidence for at least two functional forms of these molecules. Representative IgG3-binding molecules were isolated, biotinylated, and used as tracers in competitive binding assays. Cross-inhibition studies demonstrated the existence of two distinct patterns of IgG3-binding activity. Proteins of one form could be inhibited from binding to an IgG3-myeloma protein by streptococcal protein G while binding of the second form was not inhibited. These studies further underscore the extent of heterogeneity among immunoglobulin-binding proteins expressed by group A streptococci.
authors.affiliation: Department of Microbiology, Medical College of Ohio, Toledo 43699.
authors.forename: T D
authors.initials: TD
authors.lastname: Pack
authors.forename: R A
authors.initials: RA
authors.lastname: Otten
authors.forename: R H
authors.initials: RH
authors.lastname: Raeder
authors.forename: M D
authors.initials: MD
authors.lastname: Boyle
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis* / Q000502:physiology; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D009194:Myeloma Proteins / Q000378:metabolism; D017452:Receptors, IgG / Q000032:analysis*; D013297:Streptococcus pyogenes / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; C034284:IgG Fc-binding protein, Streptococcus; D007074:Immunoglobulin G; D009194:Myeloma Proteins; D017452:Receptors, IgG