Functional Analysis of the Upstream Sequence of PHO81
Gene of Saccharomyces cerevisiae

XIA Zan-Xian and AO Shi-Zhou^*
( State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry, the Chinese Academy of Sciences, Shanghai 200031, China )

Abstract　　Deletion analysis on the fused PHO81-lacZ gene revealed two important regions in the upstream sequences of PHO81 gene： －401—－289 bp and －1 012—－801 bp. They did not share higher similarity with the upstream regions of PHO5 and PHO84 gene, except that －401—－289 bp contains the 5′-CACGTG/T-3′ motif, which was found among the upstream regions of PHO5 and PHO84 gene and was the core sequence of PHO4 binding site； it also contains A/T-rich segments flanking the motif, which may be PHO2 binding sites. This suggests that the －401—－289 bp of the upstream region of PHO81 gene may contain upstream activation sequence (UAS), and －1012—－801 bp may contain upstream enhancer sequence. The gel retardation assays of the －1 012—－801 bp was performed using yeast total protein extract, and the results showed that there was an unknown protein factor binding at the region.
Key Words　　PHO81 gene; deletion analysis; retardation assay

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