<prompt> Which of following antibody is pentameric -IgMIgGIgAIgD  <response>: Ans. is a i.e., IgM Ig M is a pentameric immunoglobulin with five, four - peptide subunits. The subunits are joined together by J chain.Remember J chain is found in IgA and IgM.Also know I think the following information requires some specific mention here- There may be confusion about the status of momomer and dimer when applied to antibody as each molecule of an antibody is a dimer of two identical heavy and light chains. But, the terms monomer , dimer or pentamer are used in context to how many molecules of same class of antibody are bound together-i IgG is not found to bound to other IgG - Monomerii IgA is bound to another IgA - Dimeriii IgM binds four other IgM - Pentamer 