title: Ultrastructure of secretory and high-polymer serum immunoglobulin A of human and rabbit origin.
abstract: Electron micrographs of immunoglobulins A from human and rabbit colostrum, which were purified on tall agarose columns, revealed Y-shaped molecules (125 by 140 angstroms). The linear dimensions of the arms were 55 to 75 by 25 to 30 angstroms. A molecular model is postulated in which two immunoglobulin A monomers are superimposed on each other in a close-packed state with the secretory piece inserted in the constant region of the alpha-chains. High-polymer (11 or 13S) immunoglobulin A molecules (total span 100 to 110 angstroms) from human serum were composed of four arms (50 to 55 by 20 angstroms) joined at a contrast-rich center.
mesh_terms: D000818:Animals; D002850:Chromatography, Gel; D003126:Colostrum / Q000276:immunology*; D006801:Humans; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D007074:Immunoglobulin G / Q000032:analysis*; D007136:Immunoglobulins / Q000032:analysis; D008854:Microscopy, Electron; D008961:Models, Structural; D011817:Rabbits; D014461:Ultracentrifugation
chemical_list: D007074:Immunoglobulin G; D007136:Immunoglobulins