Synthesis, assembly and secretion of gamma globulin by mouse myeloma cells. II. Assembly of IgG_2b immunoglobulin by MPC 11 tumor and culture cells

The kinetics, pathway, and efficiency of covalent assembly of mouse IgG_2b immunoglobulin has been investigated using both tumor and cultured cells from the MPC 11 mouse myeloma. More than half of the interchain disulfide bonds were formed within three to five minutes after the synthesis and release of newly synthesized heavy and light chains and assembly was largely completed within 10 to 20 minutes after synthesis. Multiple pathways of assembly were used. Cells derived from the tumor are blocked in the covalent assembly of half molecules into IgG, but carry out the non-covalent assembly of half molecules to a higher polymer. This block in assembly may be due to the presence of a large excess of light chains rather than to a structural defect in the polypeptide chains.