Distinct regions of Sp1 modulate DNA binding and transcriptional activation

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Science  16 Dec 1988:
Vol. 242, Issue 4885, pp. 1566-1570
DOI: 10.1126/science.3059495


Sp1 is a sequence-specific DNA binding protein that activates RNA polymerase II transcription from promoters that contain properly positioned GC boxes. A series of deletion mutants of Sp1 were expressed in Escherichia coli and used to identify separate regions of the protein that are important for three different biochemical activities. The sequence-specificity of DNA binding was conferred by Zn(II) fingers, whereas a different region of Sp1 appeared to regulate the affinity of DNA binding. The E. coli-synthesized Sp1 was able to stimulate initiation of RNA synthesis in vitro, and at least two distinct segments of the protein contributed to its transcriptional activity.

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