Balanced synthesis of light and heavy chains of immunoglobulin G

WE have already investigated the production of immunoglobulin G (IgG) by mouse plasma cell tumour 5563 and have shown that light chains are released autonomously from polyribosomes into a pool of free light chains. The time course of incorporation of radioactive amino-acids into free light chain and the myeloma protein indicated that the pool of free light chains is small and reaches maximum radioactivity after about 10 min of incubation. It behaves as a pool with rapid turnover from which light chains appear to be incorporated into G myeloma protein molecules1,2. These findings led us to propose the possibility that the pool of free light chains controls the release of heavy chains from the polyribosomes.