Module 4: Figure transcription factor classification
Classification of transcription factors based on their function and mode of activation.
Some transcription factors (TFs) are always present in the nucleus and are constitutively active. The regulatory transcription factors fall into two groups. The developmentally regulated TFs are often cell-type-specific, such as those that regulate muscle differentiation (MyoD and Myf5) and those that are signal-dependent. The latter can be subdivided further on the basis of whether they are regulated by steroid hormones, internal signals or by cell-surface receptors. The cell-surface receptor-dependent TFs can be divided further into those that are resident within the nucleus, those that can shuttle between the nucleus and the cytoplasm, and the latent cytoplasmic TFs that migrate into the nucleus upon receptor activation. Modified with permission from Brivanlou, A.H. and Darnell, Jr, J.E. (2002) Signal transduction and the control of gene expression. Science 295:813–818. Copyright (2002) American Association for the Advancement of Science; see Brivanlou and Darnell 2002.