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Updated: Aug 16, 2026

Genome-wide Analysis using ChIP to Identify Isoform-specific Gene Targets
Published on: July 7, 2010
Distinct regions of Sp1 modulate DNA binding and transcriptional activation
J T Kadonaga1, A J Courey, J Ladika
1Howard Hughes Medical Institute, Department of Biochemistry, University of California, Berkeley 94720.
Abstract:
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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