Immunoglobulin M (IgM) biosynthesis was studied with mouse plasma-cell tumour MOPC 104E as a model system. Cell suspensions prepared from solid tumours were incubated in vitro with [3H]leucine; the radioactivity incorporated into intracellular and secreted proteins was analysed by sucrose-density-gradient centrifugation and polyacrylamide-gel electrophoresis. The tumour secretes IgM and light chains. ‘Pulse–chase’ experiments indicated average secretion times of 1.5h for light chain and 2.5h for IgM. The order of disulphide-bond assembly within the cell was shown to be heavy chain+light chain → heavy chain–light chain intermediate → IgMs. The 7S subunit (IgMs) was polymerized into IgM just before or at the time of secretion. Measurements of heavy-chain/light-chain radioactivity ratios in intracellular HL and IgMs and secreted IgM demonstrated the existence of a light-chain pool participating in IgM biosynthesis. The size of the light-chain pool, together with analysis of clones isolated in vivo, suggested that the tumour contains cells in which light-chain synthesis is in excess of heavy-chain production.
Research Article|July 01 1971
Immunoglobulin M biosynthesis. Production of intermediates and excess of light chain in mouse myeloma MOPC 104E
Biochem J (1971) 123 (4): 635-641.
- Views Icon Views
- PDF LinkPDF
- Share Icon Share
- Cite Icon Cite
R. M. E. Parkhouse; Immunoglobulin M biosynthesis. Production of intermediates and excess of light chain in mouse myeloma MOPC 104E. Biochem J 1 July 1971; 123 (4): 635–641. doi: https://doi.org/10.1042/bj1230635
Download citation file: