So J S, Larkins B A
Department of Plant Sciences, University of Arizona, Tucson 85721.
Plant Mol Biol. 1991 Sep;17(3):309-19. doi: 10.1007/BF00040627.
Promoter regions of alpha- and beta-zein genes were analyzed for binding of nuclear proteins from developing endosperm and seedling tissue of maize. Using a band-shift assay, we identified two distinct protein factors, alpha-1 and beta-1, that interacted specifically with alpha- and beta-zein gene promoter regions, respectively. Alpha-1 was present in nuclei from both endosperm and seedling tissue, whereas beta-1 was found only in nuclei from developing endosperm tissue. Mixing of nuclear extracts demonstrated that seedling tissue contained undetectable amounts of beta-1, rather than having an inhibitor for formation of the beta-1/DNA complex. Chemical footprinting analysis localized the beta-1 recognition site to a 22 bp sequence flanked by CCAT and TATA boxes. The apparent molecular mass of beta-1 was determined to be 29 kDa by southwestern blotting. Based on in vitro binding assays, the greatest concentration of the beta-1 in endosperm nuclei is at 16 days after pollination, which coincides with the time of highest transcriptional activity of the beta-zein gene. These results suggest that beta-1 may act as a tissue-specific, trans-acting regulator of the expression of the beta-zein gene in developing maize endosperm.
对玉米醇溶蛋白α和β基因的启动子区域进行了分析，以研究其与发育中的胚乳和玉米幼苗组织核蛋白的结合情况。通过凝胶迁移实验，我们鉴定出两种不同的蛋白质因子，α-1和β-1，它们分别与α和β玉米醇溶蛋白基因启动子区域特异性相互作用。α-1存在于胚乳和幼苗组织的细胞核中，而β-1仅在发育中的胚乳组织细胞核中发现。核提取物的混合实验表明，幼苗组织中β-1的含量极低，而不是存在抑制β-1/DNA复合物形成的抑制剂。化学足迹分析将β-1识别位点定位在一个22 bp的序列上，该序列两侧分别是CCAT盒和TATA盒。通过蛋白质免疫印迹法测定β-1的表观分子量为29 kDa。基于体外结合实验，胚乳细胞核中β-1的最大浓度出现在授粉后16天，这与β玉米醇溶蛋白基因转录活性最高的时间一致。这些结果表明，β-1可能是发育中的玉米胚乳中β玉米醇溶蛋白基因表达的组织特异性反式作用调节因子。
