B. PolylgA cousists of twomlgAmolecules linked end to eiid with J chain banding to both mlgA subunits via cysteinę (Cys) 471 of one a-chain fromeach monomer
c
1. Secretory component (SC) binds only to polymeric IgA or IgM
2. SC binding by plgA and IgM is dependent on the prcsence of J