Transcription factors are proteins that bind directly to their DNA binding sequence to elicit gene expression. Such proteins need some sort activation step, such as phosphorylation/dephosphorylation. A perfect example of activation requiring steps before the protein binds to DNA is nuclear factor Kappa B (NFkB). NFkB is sequestered outside the nucleus by a inhibitor protein termed I kappa B (IkB). IkB is then phosphorylated by IkB kinase, which is then degraded. NFkB then translocates to the nucleus, binds to DNA, and turns on inflammatory genes (genes related to immune function)such as interleukins.
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