<prompt> True about protein A of staph aureus ?Causes opsonizationBinds to Fc pa of IgGStimulate phagocytosisT-cell mitogen  <response>: Ans. is b i.e., Binds to Fc pa of IgG Protein A binds to Fc terminal of IgG IgG 1, 2 4 but not IgG3 and prevents opsonophagocytosis by PMNs.It is a B-cell mitogen. It is chemotactic, anti-complementory and antiphagocytic. 