title: Naturally occurring polymers of IgA lacking J chain.
abstract: Two of twenty IgA myeloma proteins studied were found to lack J chain. Both IgA proteins contained dimers and higher polymers (trimers, tetramers, pentamers) in proportions similar to those found in most classical 'J-positive' proteins. Both the 'J-negative' proteins contained bound albumin and alpha-1 antitrypsin (alpha1AT),and reduction with mercaptoethylamine caused a release of albumin and alpha1AT concomitant with depolymerization of the higher polymers of IgA. These proteins formed complexes with secretory component (SC) in vitro, indicating that the presence of J chain is not a requirement for SC binding.
mesh_terms: D001665:Binding Sites; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis*; D007144:Immunoglobulin J-Chains / Q000032:analysis*; D009101:Multiple Myeloma / Q000276:immunology; D011108:Polymers; D012635:Secretory Component / Q000032:analysis; D014461:Ultracentrifugation
chemical_list: D007070:Immunoglobulin A; D007144:Immunoglobulin J-Chains; D011108:Polymers; D012635:Secretory Component