Characterization of a nuclear factor that enhances DNA binding activity of SSCRE-BP/PUR alpha, a single-stranded DNA binding protein.

Pur alpha has been identified as a single-stranded DNA binding protein that specifically binds to the purine-rich strand present in the DNA replication initiation zone of the human c-myc gene. We have previously demonstrated that chronic morphine treatment decreases the DNA binding activity of ssCRE-BP (single-stranded cyclic AMP response element-binding ...
protein), which has been shown to be identical to pur alpha by cDNA cloning, and is abundant in the brain. In this report we identified an activator of ssCRE-BP/pur alpha in the brain and characterized it. Although purified ssCRE-BP/pur alpha or its GST-fusion protein exhibited very low DNA binding activities, they were markedly enhanced by including nuclear extract in the binding assay. The enhanced binding activity is trypsin-sensitive, heat-stable and has a molecular weight of approximately 66 kDa. Casein could substitute for the activator and increased the DNA binding activity of ssCRE-BP/pur alpha by one order. A series of deletion mutants were prepared in order to determine the DNA binding and activator interacting domains, and both of them were found to reside in AA 50-215 of ssCRE-BP/pur alpha. These data suggest that the DNA binding activity of ssCRE-BP/pur alpha is augmented by a nuclear protein, which may modulate the ssCRE-BP/pur alpha activity to develop morphine dependence and tolerance.
Mesh Terms:
Animals, Biological Factors, Caseins, Cell Nucleus, Cerebellum, Cyclic AMP Response Element-Binding Protein, DNA-Binding Proteins, Mice, Molecular Weight, Mutation, Nerve Tissue Proteins, Protein Structure, Tertiary, Transcription Factors
Neurochem Int
Date: Jul. 01, 1997
Download Curated Data For This Publication
226753
Switch View:
  • Interactions 1