Proteins that are able to bind to DNA in both eukaryotes and prokaryotes and act as either activators or repressors of gene expression by controlling the binding of RNA polymerase to DNA during the process of transcription (see transcription factor). They are also involved in DNA replication: by binding to the nucleotides in the single DNA strands of the template that have unwound, they stabilize these strands so that they do not rewind. DNA-binding proteins do not include the histones.