mRNA for H and L Chains of Immunoglobulin: Specific Control of H-Chain Production
Messenger RNA (mRNA) was postulated to exist in prokaryotic systems by Jacob and Monod (1961) on the basis of genetic evidence. Extensive studies since that time have proven the universality of the transfer of information from DNA to a messenger RNA which is then translated to give protein. In prokaryotic systems there is a direct coupling of the transcription of the genes into RNA to the translation of that RNA into protein. This elegant and simple coupling provides a regulatory mechanism at several defined stages of protein synthesis. Regulation occurs notably at the level of transcription, via repressor proteins binding directly to the DNA (Ptashne, 1967; Gilbert and Müller-Hill, 1967). It is clear that eukaryotic cells provide more potential sites for control of protein synthesis. The flow of information from the gene (Fig. 1) can be regulated at the following levels: (a) selection of the appropriate genes to be transcribed, (b) processing within the nucleus of the primary RNA transcript, (c) transport of the processed messenger RNA from the nucleus to the cytoplasm, and (d) control of the translation of mRNA in the cytoplasm. Prokaryotic mRNA appears to be an ephemeral species which may never exist as a completed molecule since its degradation can start before its completion. By contrast, mRNA in eukaryotic cells is a long-lived species. Following a brief existence in the nucleus in the form of a precursor RNA molecule, functional mRNA is transported to the cytoplasm, where it has a lifetime ranging from hours to days (Greenberg, 1972). During the long lifetime of mRNA in the cytoplasm there is ample scope for variation in the rate of translation.
KeywordsMyeloma Cell Specific Control mRNA Molecule Myeloma Protein Mouse Myeloma Cell
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- Dayhoff, M. O., 1969, The Atlas of Protein Sequence and Structures, Vol. 4, National Biomedical Research Foundation, Silver Spring, Md.Google Scholar
- Jelinek, W., Adesnik, M., Salditt, M., Sheiness, D., Wall, R., Molloy, G., Philipson, L., and Darnell, J. E., 1973, J. Mol. Biol. 73: 515.Google Scholar
- Lodish, H., 1971, J. Biol. Chem. 246: 7131.Google Scholar
- Molloy, G., Sporn, M. B., Kelley, D. E., and Perry, R. P., 1972, Biochemistry 11: 3256.Google Scholar
- Palmiter, R., 1972, J. Biol. Chem. 247: 6770.Google Scholar
- Premkumar, E., Stevens, R. H., and Williamson, A. R., 1973, in preparation.Google Scholar
- Stevens, R. H., and Williamson, A. R., 1973c, J. Mol. Biol. 78: 516.Google Scholar