NURSING ANM AND GNM

Detailed explanation-1: -IgA has the capacity to form dimers, in which two monomer units, each comprising two heavy chains and light chains, are arranged in an end-to-end configuration stabilized by disulphide bridges and incorporation of J (joining) chain.

Detailed explanation-2: -Serum IgA molecules are mostly monomeric, while secretory IgA molecules are found as dimers and, to a lesser extent, as trimers and tetramers. In the dimer, two IgA molecules are linked together by another polypeptide designated as J-chain.

Detailed explanation-3: -SIgA is a polymeric antibody, typically containing two copies of IgA that assemble with one joining-chain (JC) to form dimeric (d) IgA that is bound by the polymeric Ig-receptor ectodomain, called secretory component (SC).

Detailed explanation-4: -Like all Igs, IgA molecules are made up of pairings of two identical heavy chains (-chains in the case of IgA) and two identical light chains. In humans, the IgA in serum is chiefly monomeric, comprising ∼90% IgA1 and 10% IgA2 (Figure 1a and b). Further heterogeneity arises because both subclasses can form dimers.