Two rapidly labeled RNA species in the polysomes of antibody-producing lymphoid tissue.

Popliteal lymph nodes of rabbits stimulated to produce antibodies were pulse labeled in vivo by direct injection of (3)H-uridine. RNA was then extracted from isolated polysomes and single ribosomes. Fractionation of this RNA by polyacrylamide gel electrophoresis revealed the synthesis of two discrete peaks of labeled RNA migrating in the region between 18S ribosomal and 4S transfer RNA. These peaks were found in the RNA extracted from polysomes but were absent from single ribosomes. When the polysomes were disrupted by EDTA treatment the RNA species no longer appeared as rapidly sedimenting material. These two RNA's have molecular weights near 2.2 x 10(5) and 3.7 x 10(5) daltons. The chemical and biological properties of these species as well as the molecular weights are consistent with those expected for monocistronic messenger RNA coding for the antibody L and H chains, respectively.