Detection and purification of the promoter region-binding protein involved in the tissue-specific gene expression

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In thid laboratory, several genomic clones as well as cDNA clones of rat liver enzymes involved in amino acid metabolism have been isolated. Among them, serine dehydratase is the inducible enzyme, whose activity is subject to change by the treatment of various hormones or by feeding various composition of diet. To learn the molecular mechanim of enzyme induction/suppression, we attempoted to clone the serine dehydratase cDNA. One clone was screened from a gtll library carrying rat licer cDNAs. The cDNA was found to encode 363 amino acids and the expected molecular weight atrees well that obtained previously by sds/page of the purified protein. We also obtained the corresponding genomic clones and determined their DNA sequence. The serine dehydratase gene consisted of 9 exons and 8 introns, whose boundary sequences are obeyed by a gt/ag rule. The 5' flanking region of the gene contains a variety of sequences that are similar to the consensus elements which are proved to aggect the transcription of other genes. Two sequences similar to glucocorticoid response element are located at positions -2240 and -280. Since serine dehydratase is under control by glucagon and dexamethasone, the occurrence of such sequences is quiet reasonable. to prove the function of these sequences and to look for the specific factors which might regulate the gene transcription, we are developing the in vitro transcription system usin unclear extracts obtained from rat licers maintained on various diets, and the g-less cassette vector (gorski et al. 1987) having fragments of the 5' flanking region of the serine dehydratase gene.