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?


1 Answer 1


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.

  • $\begingroup$ I added one more confusing statement which I do not understand about S.pyogenes. Do you understand AG there? $\endgroup$ Commented Feb 6, 2014 at 18:49
  • 2
    $\begingroup$ en.wikipedia.org/wiki/Lancefield_grouping "a method of grouping beta haemolytic bacteria based on the carbohydrate composition of bacterial antigens found on their cell walls." $\endgroup$
    – Alan Boyd
    Commented Feb 6, 2014 at 20:11

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .