The Ovalbumin Genes

The ovalbumin gene, shown here, has introns A to G and exons 1 to 7 and L (L encodes a signal peptide sequence that targets the protein for export from the cell see Fig. 27-34). About three-quarters of the... 

Production of a large amount of a single type of protein by means of a prolonged mRNA lifetime is common in highly differentiated cells. For example, cells of the chicken oviduct, which makes ovalbumin (for egg white), contain only a single copy of the ovalbumin gene per haploid set of chromosomes, but the cellular mRNA is long lived. 

Since E. coli lack the machinery to excise introns and splice exons, they would make a meaningless mRNA if presented with ovalbumin genomic DNA. Therefore, if you wish to express the ovalbumin gene in E. coli, you must use its cDNA, which contains the information in the eight exons, but no introns. 

Upstream of the ovalbumin gene are two genes, X and Y, which are homologous with the ovalbumin gene and have arisen by gene duplication. All three are contained within 46 kb DNA. All three genes are under steroid hormonal control, and all three are expressed in the oviduct of the laying hen, but X and Y at only about 2% the level of ovalbumin mRNA (LeMeur et al, 1981). 

Bloom, K.S. Anderson, J.N. (1982). Hormonal regulation of the conformation of the ovalbumin gene in chick oviduct chromatia ]. Biol Chem., 257, 13018-27. 

LeMeur, M., Glanville, N., Mandel, J.L., Gerlinger, P., Palmiter, R. Chambon, P. (1981). The ovalbumin gene family hormonal control of the X and Y gene transcription and mRNA accumulation. Cell, 23, 561-71. 

Structure and Hormonal Regulation of the Ovalbumin Gene Cluster Bert W. O Malley, Savio L. C. Woo, and Ming-Jer Tsai... 

We checked this fact also in the case of the ovalbumin gene, for which terminal parts of the intron sequence are known . 

Benoist, C., O Hare, K., Breathnach, R., and Chambon, P., 1980, The ovalbumin gene-sequence of putative control regions, Nucl. Acids Res. 8 127-142. 

Tsai, S. Y., Tsai, M.-J., and O Malley, B. W., 1981/ , Specific 5 -flanking sequences are required for faithful initiation of in vitro transcription of the ovalbumin gene, Proc. Natl. Acad. Sci. USA 78 879-883. 

It has been shown that, during secondary stimulation with estrogen, there is an increase in the concentration of nuclear receptor molecules followed by an increase in the available initiation sites for RNA synthesis on the chromatin (Tsai et al., 1975b Kalimi et al., 1976 Anderson et al., 1972). Using hybridization techniques, it has been shown that control of the expression of the ovalbumin gene by estrogen occurs at the transcriptional level (Harris et al., 1976). 

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