We report the cloning of a human complementary DNA that encodes a protein which exhibits 36% identity and 62% similarity to Escherichia coli ribosomal protein S1 (rpS1), including conservation of four copies of an RNA-binding domain. This clone was obtained by ligand-screening a λgt11 expression library with a DNA probe derived from the CYBB gene promoter. Electrophoretic mobility shift and Southwestern blot assays confirm DNA binding activity of the protein, which exhibits preferential binding to single-stranded and double-stranded DNA and a low binding affinity for RNA. Hence, the rpS1 protein domain previously identified as an RNA-binding motif can also serve as a DNA-binding domain.
- Escherichia coli
- Glutathione S-transferase fusion protein
- Southwestern blot
- ligand screen
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