We cloned the cDNA of human αs1-casein, a minor protein component in human milk, from human breast mRNA and identified its nucleotide sequence. In an attempt to characterize its expression in mammary gland tissue, RT-PCR and Northern blot analysis were done with human milk epithelial cells from a lactating woman. A positive expression band was detected by RT-PCR and verified by Northern hybridization using a cDNA probe corresponding to nucleotides 1-974 of human αs1-casein cDNA. It has been reported that the human αs1-casein gene is not expressed in human tissue samples from brain, heart, kidney, lung, pancreas, placenta, skeletal muscle, colon, leukocytes, ovary, prostate, small intestine, spleen, testis and thymus (Johnson et al. Biochem J 1995;309:237). This strongly suggests that the gene is expressed specifically in human mammary gland epithelial cells. In order to explore its biological function using recombinant protein, we recombined the cDNA of the mature protein into the E. coli vector pKK223-3. SDS-PAGE showed a highly induced band at the same position as the human αs1-casein band from human milk. We are presently exploring factors affecting its expression.
|Original language||English (US)|
|State||Published - 1997|
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology