Purification of an antibody-like protein from the sea star Asterias rubens (L.).
Cells from sea star (Asterias rubens) axial organs stimulated with trinitrophenyl (TNP) or fluoresceinyl-haptened polyacrylamide beads and subsequently stimulated in vitro with the same antigen produced and released a specific antibody-like protein which induced lysis of haptened sheep erythrocytes in the presence of serum complement. The anti-TNP antibody-like protein isolated by ammonium sulfate precipitation, gel filtration and affinity chromatography exhibited a single precipiting peak after crossed immunoelectrophoresis against rabbit antiserum to partially purified culture supernatant. The anti-TNP antibody-like protein gave a specific affinity precipitate in crossed affino-electrophoresis using a p-nitrobenzoyl-substituted gel. The analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under both reducing and nonreducing conditions evidenced a unique 30-kDa polypeptide chain. According to gel filtration experiments, the molecular weight of the major component isolated by affinity chromatography was about four times higher. Therefore, the antibody-like molecule could be a tetrameric protein devoid of any disulfide bond.
D000818:Animals; D000941:Antigens / Q000276:immunology; D002478:Cells, Cultured; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D006241:Haptens / Q000276:immunology; D005779:Immunodiffusion; D007447:Invertebrate Hormones / Q000276:immunology / Q000302:isolation & purification*; D008221:Lymphoid Tissue / Q000032:analysis / Q000166:cytology / Q000276:immunology; D013215:Starfish / Q000276:immunology*
D000941:Antigens; D006241:Haptens; D007447:Invertebrate Hormones