Staphylococcus AG structure? I found this statement in my study materials in the section of Staphylococcus > The AG structure: > > * protein AG (species specific); > * polysaccharide AG (serotype specific). > I know what is Protein A/G, a recombinant fusion protein that combines IgG binding domains of both Protein A and Protein G. **What is the point of this AG structure thing in the contex of Staphylococcus?** Can we say that staphylococcus have AG structure? I think it has properties related to protein A\G and also to polysaccharide A\G. I know very little about polysaccharide A\G and not sure how it is related to serotype specificity in the context of staphylococcus. **Extension to the question** Antigenic structure of Steptococcus pyogenes: the group AG is unique, placing streptococcus in group A. **What is the AG here?**

After puzzling over this for a while I think I have the answer . It's nothing to do with protein A or protein G. I think that whoever wrote your study materials meant Ag which is a common abbreviation for 'antigen'. I guess this was in the context of immune responses, or strain typing.

Looking back over your last few questions, it seems that you are at the mercy of a teacher who specialises in ambiguity.