[Isolation, characterization, and translation of heterogeneous nuclear RNA from plasmacytoma cells]

It was found that during hot phenol fractionation of plasmacytoma MOPC-21 cells, which produce immunoglobulins of gamma 1 chi-type, separation of nuclear and nucleolar RNAs, differing in kinetics of accumulation of radioactive precursors, distribution during gradient centrifugation procedures and in base composition, takes place. D-RNA 63 degrees and D-RNA 85 degrees, which possess similar characteristics with D-RNAs, discovered earlier in other cells were isolated. It was stated, the D-RNA 85 degrees is considerably enriched by 3'-terminal poly(A) sequences in comparison with D-RNA 63 degrees. During translation in cell-free protein synthesising system from Xenopus oocytes, these two fractions of hnRNA induced formation of immunospecific products. D-RNA 85 degrees stimulated synthesis of gamma 1 and chi chains more efficiently, that D-RNA 63 degrees. Polyadenylated and non-adenylated both D-RNAs stimulated synthesis gamma 1 and chi chains of immunoglobulin G1 during translation. This fact indicates the absence of significant differences in the informational content. These results give opportunity to propose the existence of two levels of processing pre-mRNA for immunoglobulin chains.