Translation affects immunoglobulin mRNA stability

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Abstract
When termination codons were introduced into exons of the gene for Ig m̈ chain, steady‐state levels of m̈ mRNA were reduced, both at the pre‐B cell stage and at the plasma cell stage. A termination codon in the variable region gene segment and a termination codon in the second exon of the constant region gene segment had effects of similar magnitude. When the termination codon was deleted, the original level of mRNA was restored. The rate of m̈ gene transcription was the same whether or not a termination codon was present. Therefore, the termination codons must reduce the amount of the mRNA by reducing its stability. Since the introduced termination codons prematurely terminate translation and, in so doing, change the ribosome load on the mRNA, we conclude that m̈ mRNA stability is conferred in part by ribosomal protection from enzymatic degradation. We propose that the differences in m̈ mRNA stability during B lymphocyte differentiation are due to different amounts of ribosomes available for translation.