title: An examination of the "star-phenomenon", a three component immunoprecipitation involving staphylococcal protein A.
abstract: The co-precipitation called "star-phenomenon" occurred between the three component system: protein A, an IgG forming soluble complexes with protein A and F (ab')2-preparations of human IgG, guinea pig IgG or rabbit anti-staphylococcal IgG. Co-precipitation also occurred if the IgG was replaced by normal human Fc fragments. On a protein A column the human F (ab')2-preparation was separated into a major non-reactive and a minor reactive fraction. Only the latter contained Fc-structures, these being isolated on an anti-Fc column and found to belong to undigested IgG. The "star"-forming protein A reactive F (ab')2-fragments were washed through the anti-Fc column. The F (ab')2 fraction from rabbit anti-staphylococcal IgG contained no Fc-structures and only a small portion containing anti-protein A activity was active in co-precipitation.
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000276:immunology*; D011232:Chemical Precipitation; D006168:Guinea Pigs / Q000276:immunology; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000032:analysis; D007141:Immunoglobulin Fc Fragments / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D011817:Rabbits / Q000276:immunology; D013210:Staphylococcus / Q000276:immunology
chemical_list: D001426:Bacterial Proteins; D007140:Immunoglobulin Fab Fragments; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G