title: Synthesis but not secretion of J chain by variant mouse myeloma cells which lose alpha-chain-synthesizing ability.
abstract: We have devised a rapid method for obtaining large amounts of J chain from IgA in the ascitic fluid of mice bearing the MOPC 315 tumor. The J chain was released by reduction from the MOPC 315 IgA adsorbed onto a DNP-lysyl-Sepharose column, and was further purified by DEAE Sephadex chromatography. The mouse J chain was characterized as to its electrophoretic mobility, amino acid composition, apparent size, presence in different immunoglobulin classes, and reactivity with an antiserum containing anti-J chain activity. Variant cell lines have been selected from the IgA-producing mouse myeloma cell line MOPC 315. The variants did not synthesize detectable quantities of alpha heavy chains but continued to synthesize and secrete light chains. J chain was synthesized by both parent and variant cell lines but only secreted by the parent cells. It is postulated that J chain synthesis is not dependent on alpha heavy chain synthesis, but that secretion of J chain by MOPC 315 cells occurs only because of its attachment to the Ig1 molecule.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001202:Ascitic Fluid / Q000276:immunology; D002460:Cell Line; D011232:Chemical Precipitation; D002999:Clone Cells / Q000032:analysis / Q000378:metabolism; D003593:Cytoplasm / Q000276:immunology; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D007106:Immune Sera / Q000302:isolation & purification; D007070:Immunoglobulin A / Q000302:isolation & purification; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis*; D007144:Immunoglobulin J-Chains / Q000032:analysis* / Q000302:isolation & purification; D007147:Immunoglobulin Light Chains / Q000096:biosynthesis; D007137:Immunoglobulin alpha-Chains / Q000096:biosynthesis*; D007146:Immunoglobulin lambda-Chains / Q000302:isolation & purification; D051379:Mice; D008807:Mice, Inbred BALB C; D009101:Multiple Myeloma / Q000276:immunology*; D009374:Neoplasms, Experimental
chemical_list: D000596:Amino Acids; D007106:Immune Sera; D007070:Immunoglobulin A; D007143:Immunoglobulin Heavy Chains; D007144:Immunoglobulin J-Chains; D007147:Immunoglobulin Light Chains; D007137:Immunoglobulin alpha-Chains; D007146:Immunoglobulin lambda-Chains