Structural characterization of a human monoclonal IgA protein

Abstract

The serum of an IgA myeloma patient was found to contain at least 90% of the monoclonal protein as a 10·05S disulphide-bonded dimer. Small amounts of monomeric and higher oligomeric forms were also observed. Light chains were κ type, disulphide-bonded to heavy chains and preferentially released upon reduction with dithioerithritol.

Electron microscopy of the dimer and oligomeric forms showed structures suggesting linkage between Y-shaped monomer units via the terminus of the Fc fragment. The data is discussed in relation to secretion of the different oligomeric forms.