Synthesis of immunoglobulins by membrane-bound polysomes and free polysomes from plasmacytoma cells.

Abstract

Free polysomes and membrane‐bound polysomes were prepared from tissue‐cultured mouse plasmacytoma cells and interacted with 125I‐labelled F(ab) fragments of rabbit antibody to the mouse myeloma proteins. Peaks of reactive polysomes were found in the 6–8 oligomer and 16–20 oligomer region of membrane‐bound polysomes but not of free polysomes. When used in an amino‐acid‐incorporating system in vitro, membrane‐bound polysomes gave rise primarily to light‐chain immunoglobulins which were identified after reduction and acetylation and separation on dodecylsulfate‐gel electrophoresis, but free polysomes did not. Polysomes associated with synthesis of immunoglobulin, a secreted protein, appear to be entirely in the membrane‐bound fraction.