A molecular model of transcription factor, a protein that binds to DNA sequences during transcription, the process of DNA replication into RNA. Transcription factor interprets genetic sequences to regulate the process and rate of copying DNA, determining gene expression. For DNA, base pairs are colored red (cytosine), green (guanine), yellow (thymine) and blue (adenine). Atoms in the double helix are colored dark gray (carbon), orange (phosphorus) and red (oxygen). Transcription factor proteins are colored light blue.