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The same nuclear proteins bind to the 5'-flanking regions of genes for the rice seed storage protein: 16 kDa albumin, 13 kDa prolamin and type II glutelin.
Expression of rice seed storage-protein genes is dramatically regulated over a short period of seed maturation. To characterize the expression mechanism of the rice seed storage protein genes, their expression of major storage protein genes (16 kDa albumin, 13 kDa prolamin and type II glutelin) were compared by RNA blot analysis. Their coordinate expression suggests that the transcriptional regulatory machinery is shared among the glutelin, prolamin and albumin-genes. We isolated two novel genomic genes for prolamins (PG5a and PG5b) and obtained the promoter region of the glutelin gene by PCR. The 5'-flanking regions of these three rice seed storage protein genes were found to contain some similar conserved sequences. Nuclear extract partially purified from maturing rice seeds was used for the gel shift assay of the 5' region of the RA gene. We identified two DNA sequences of RA gene which were recognized by independent DNA-binding proteins. The complexes of these DNA sequences and DNA-binding proteins were inhibited by the fragments containing the 5' regions of the prolamin and glutelin genes, suggesting that these three genes share transcription factors.
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