Binding of 125I-labeled anti-L chain to polysomes of rat spleen in vitro

Abstract

The light (L) chain of rat gamma globulin was isolated and injected into rabbits as antigen. Fractionated immune gamma globulin from the rabbits was labeled with 125I and used to indicate the presence of nascent L chains on ribosomes of rat spleen. After centrifugation in a sucrose gradient, the label was found on ribosomes containing 4 to 9 monomeric units, but was not coincident with the optical density profile (OD). The highest specific activity was found between the hexamer and the septamer or between the septamer and octamer. During the first 24 hours of the immune response to sheep erythrocytes, the amount of 125I anti-L chain bound to ribosomes decreased to a minimal value 12 hours after injection of antigen and increased between 12 and 24 hours to a value comparable to that in nonimmunized animals.