The synthesis and processing of the messenger RNAs specifying heavy and light chain immunoglobulins in MPC-11 cells

摘要: Abstract The nuclear precursors of the immunoglobulin messenger RNAs MPC-11 cells were characterized with respect to size, amount per cell and extent polyadenylation. These produce three Ig mRNAs: a 1.8 kb component coding for γ 2b heavy chain (H mRNA), 1.2 mRNA κ light (L mRNA) 0.8 constant region portion 1 mRNA). To identify pre-mRNAs without ambiguity, we constructed recombinant DNA plasmids containing H L cDNA sequences, used cloned cDNAs as hybridization probes analysis steady state RNA in excess experiments pulse-labeled RNA. molecules sequences consist an 11 ), which believe be primary transcript gene, 5.3 3.3 2 ) components, seem transcripts genes, components corresponding mature size H, mRNAs, several intermediatesized include processing derivatives. precursor role these was established by studies their labeling kinetics appropriate pulse-chase experiments. All pre-mRNA species including , contain poly(A), thus suggesting that polyadenylation is early event mRNAs. contains about 30,000 40,000 cytoplasmic molecules, respectively, must produced within one generation (∼24 hr). In comparison, nucleus 100–150 total only 10–15 presumptive each species. values indicate very rapid transcription rates (>20 min) exceptionally fast (∼0.5 min ∼5 overall processing) Thus processing, together high stability, account abundance mRNAs myeloma cell.