What are the 3 transcription factors?
Many transcription factors are either tumor suppressors or oncogenes, and, thus, mutations or aberrant regulation of them is associated with cancer. Three groups of transcription factors are known to be important in human cancer: (1) the NF-kappaB and AP-1 families, (2) the STAT family and (3) the steroid receptors.
What are transcription factors in transcription?
Transcription factors are proteins involved in the process of converting, or transcribing, DNA into RNA. Transcription factors include a wide number of proteins, excluding RNA polymerase, that initiate and regulate the transcription of genes.
What are the 5 general transcription factors in eukaryotes?
The holoenzyme consists of a preformed complex of RNA polymerase II, the general transcription factors TFIIB, TFIIE, TFIIF, and TFIIH, and several other proteins that activate transcription.
What is an alternative sigma factor?
Alternative bacterial sigma factors bind the catalytic core RNA polymerase to confer promoter selectivity on the holoenzyme. The different holoenzymes are thus programmed to recognize the distinct promoter classes in the genome to allow coordinated activation of discrete sets of genes needed for adaptive responses.
Are repressors transcription factors?
Repressors decrease transcription. Groups of transcription factor binding sites called enhancers and silencers can turn a gene on/off in specific parts of the body. Transcription factors allow cells to perform logic operations and combine different sources of information to “decide” whether to express a gene.
What is a eukaryotic transcription factor?
Eukaryotic transcription factors are modular proteins that utilize distinct domains for transcriptional activation (or repression) and DNA binding. Transcription factors are often purified and cloned based on their specific binding sequences.
How do sigma factors work?
The sigma factor allows the RNA polymerase to properly bind to the promoter site and initiate transcription which will result in the production of an mRNA molecule. Once the role of the sigma factor is completed, the protein leaves the complex and RNA polymerase will continue with transcription.
Is p53 a transcription factor for p21?
As a bona fide transcription factor, p53 transactivates its target genes in response to these stresses, resulting in cell-cycle arrest, senescence, or apoptosis, to prevent the proliferation of damaged cells. The best known examples of such targets include p21 and MDM2.
What causes upregulation of p53?
The genes affected in these mutants function in diverse cellular processes, yet their disruption universally leads to p53 upregulation. It is known that p53 can be activated by various stress signals. p53 response to DNA damage was especially thoroughly studied.
How do repressors affect transcription?
In molecular genetics, a repressor is a DNA- or RNA-binding protein that inhibits the expression of one or more genes by binding to the operator or associated silencers. A DNA-binding repressor blocks the attachment of RNA polymerase to the promoter, thus preventing transcription of the genes into messenger RNA.