CLONING OF A CDNA-ENCODING A HUMAN DNA-BINDING PROTEIN SIMILAR TO RIBOSOMAL-PROTEIN S1

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 lambda gt11 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.