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The gene for {gamma}-casein, a milk protein, is a member of a family of casein gene which is expressed in mammary glands of the animal during the late gestation and lactation periods binder the influence of various hormones. In order to elucidate tile mechanisms b)’which hormones regulate the coordinate induction of milk protein genes, the mouse {gamma}-casein gene was isolated and characterized. The {gamma}-casein gene was screened from a mouse genomic library constructed in bacteriophage EMBL3 with the {gamma}-casein CDNA used as probe and one clone was obtained. The {gamma}-casein CDNA as probe was partially sequenced and contained ATG start codon and 5’-noncoding region. The cloned genomic DNA was digested with Sal I restriction enzyme, by which the insert DNA can be isolated from EMBL3 vector. Three DNA bands were observed and the size of DNAs was approximately 28kb, 14kb and 9Kb, respectively Accordingly the size of the insert DNA was calculated with approximately 23Kb. The result of Southern blot analysis, however, showed that the cloned genomic DNA was not hybridized with the synthetic oligonucleotides (40 mer) of cDNA 5’-end region, but it was hybridized with the y -casein CDNA. This means that tile cloned y -casein gene may not contain its promoter region. The {gamma} -casein genomic DNA containing the promoter region has been screening from mouse genomic library with oligonucleotides of CDNA 5’-end region as probe, and twenty-nine clones was obtained.
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