In molecular biology, transcription factors (TF) (or sequence-specific DNA binding factors) are proteins that control the rate of transcription of genetic information from DNA to messenger RNA by binding to specific DNA sequences. The function of TFs is to regulate - turn genes on and off to ensure they are expressed in the right cells at the right time and in the right amount throughout the life cycle of the cell and organism. The TF group acts in a coordinated manner to direct cell division, cell growth and cell death throughout life; cell migration and organization during embryonic development (physical planning); and intermittent response to signals from outside the cell, such as hormones. There are as many as 2,600 TFs in the human genome.
TFs act alone or in conjunction with other proteins in the complex by promoting (as an activator) or blocking (as a repressor) RNA polymerase (an enzyme that transcribes genetic information from DNA to RNA) to the recruitment of specific genes. A defining feature of TF is that they contain at least one DNA binding domain (DBD) attached to a particular DNA sequence adjacent to the gene they regulate. The TF is classed according to its DBD grouping. Other proteins such as coactivators, chromatin remodeling proteins, histone acetyltransferases, histone deacetylases, kinases and methylases are also required for gene regulation, but lack DNA binding domains and are therefore not TF. TF is of great interest to medicine because TF mutations can cause specific diseases and drugs may potentially target them.
Transcription factors bind to enhancers or promoter regions of DNA adjacent to their regulated genes. According to transcription factors, transcription of adjacent genes can be upregulated or downregulated. Transcription factors use a variety of mechanisms to regulate gene expression. These mechanisms include:
Transcription factors are one of the proteomes that read and interpret genetic "blueprints" in DNA. They bind to DNA and help initiate the process of increasing or decreasing gene transcription. Therefore, they are critical to many important cellular processes.
Transcription Factors in the Akt Pathway
Signal transduction often culminates in the activation of transcription factors, a specialized subset of proteins capable of interacting with DNA to either up- or downregulate the transcription of genes. Transcription factor binding is often specific for certain DNA sequences. They are highly regulated with respect to cytoplasmic vs. nuclear localization, stabilization, and post-translational modification. The transcription factors listed below have all been associated with Akt pathway activation, which promotes cell growth, survival, proliferation, autophagy, and metabolism. The activity of these transcription factors is either up- or downregulated by Akt signaling.
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