transcription factor


transcription factor

      molecule that controls the activity of a gene by determining whether the gene's DNA (deoxyribonucleic acid) is transcribed into RNA (ribonucleic acid). The enzyme RNA polymerase catalyzes the chemical reactions that synthesize RNA, using the gene's DNA as a template. Transcription factors control when, where, and how efficiently RNA polymerases function.

 Transcription factors are vital for the normal development of an organism, as well as for routine cellular functions and response to disease. Transcription factors are a very diverse family of proteins (protein) and generally function in multi-subunit protein complexes. They may bind directly to special “promoter” regions of DNA, which lie upstream of the coding region in a gene, or directly to the RNA polymerase molecule. Transcription factors can activate or repress the transcription of a gene, which is generally a key determinant in whether the gene functions at a given time.

      Basal, or general, transcription factors are necessary for RNA polymerase to function at a site of transcription in eukaryotes (eukaryote). They are considered the most basic set of proteins needed to activate gene transcription, and they include a number of proteins, such as TFIIA (transcription factor II A) and TFIIB (transcription factor II B), among others. Substantial progress has been made in defining the roles played by each of the proteins that compose the basal transcription factor complex.

      During development of multicellular organisms, transcription factors are responsible for dictating the fate of individual cells. For example, homeotic genes control the pattern of body formation, and these genes encode transcription factors that direct cells to form various parts of the body. A homeotic protein can activate one gene but repress another, producing effects that are complementary and necessary for the ordered development of an organism. If a mutation occurs in any of the homeotic transcription factors, an organism will not develop correctly. For example, in fruit flies ( Drosophila), mutation of a particular homeotic gene results in altered transcription, leading to the growth of legs on the head instead of antenna; this is known as the antennapedia mutation.

      Transcription factors are a common way in which cells respond to extracellular information, such as environmental stimuli and signals from other cells. Transcription factors can have important roles in cancer, if they influence the activity of genes involved in the cell cycle (or cell division cycle). In addition, transcription factors can be the products of oncogenes (oncogene) (genes that are capable of causing cancer) or tumour suppressor genes (tumour suppressor gene) (genes that keep cancer in check).

      Transcription factors function in the nucleus, where genes are found, and nuclear transport (i.e., import or export) of transcription factors can influence their activity. Another important general mechanism controlling the activity of transcription factors is posttranslational modification such as phosphorylation. Finally, in addition to controlling the genes and transcription of other transcription factors, these protein complexes can also control the genes responsible for their own transcription, leading to complex feedback control mechanisms.

John A. Cooper
 

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Universalium. 2010.

Look at other dictionaries:

  • Transcription Factor II B — (TFIIB) is one of several general transcription factors that make up the RNA polymerase II preinitiation complex.cite book | author = Lewin, Benjamin | title = Genes VIII | publisher = Pearson Prentice Hall | location = Upper Saddle River, NJ |… …   Wikipedia

  • Transcription Factor II D — (TFIID) is one of several general transcription factors that make up the RNA polymerase II preinitiation complex.cite book | author = Lewin, Benjamin | title = Genes VIII | publisher = Pearson Prentice Hall | location = Upper Saddle River, NJ |… …   Wikipedia

  • transcription factor — n any of various proteins that bind to DNA and play a role in the regulation of gene expression by promoting transcription * * * a protein that regulates gene expression by binding to a DNA sequence adjacent to a sequence encoding a protein or… …   Medical dictionary

  • Transcription factor — In the field of molecular biology, a transcription factor (sometimes called a sequence specific DNA binding factor) is a protein that binds to specific sequences of DNA and thereby controls the transfer (or transcription) of genetic information… …   Wikipedia

  • Transcription Factor II F — protein Name = general transcription factor IIF, polypeptide 1, 74kDa caption = width = HGNCid = 4652 Symbol = GTF2F1 AltSymbols = TFIIF, BTF4, RAP74 EntrezGene = 2962 OMIM = 189968 RefSeq = NM 002096 UniProt = P35269 PDB = ECnumber = Chromosome …   Wikipedia

  • Transcription Factor II A — protein Name = general transcription factor IIA, 1, 19/37kDa caption = width = HGNCid = 4646 Symbol = GTF2A1 AltSymbols = EntrezGene = 2957 OMIM = 600520 RefSeq = NM 201595 UniProt = P52655 PDB = ECnumber = Chromosome = 14 Arm = q Band = 31… …   Wikipedia

  • Transcription Factor II E — protein Name = general transcription factor IIE, polypeptide 1, alpha 56kDa caption = width = HGNCid = 4650 Symbol = GTF2E1 AltSymbols = TF2E1 EntrezGene = 2960 OMIM = 189962 RefSeq = NM 005513 UniProt = P29083 PDB = ECnumber = Chromosome = 3 Arm …   Wikipedia

  • Transcription Factor II H — protein Name= general transcription factor IIH, polypeptide 1, 62kDa caption= width= HGNCid=4655 Symbol=GTF2H1 AltSymbols= BTF2 EntrezGene=2965 OMIM=189972 RefSeq=NM 005316 UniProt=P32780 PDB= ECnumber= Chromosome=11 Arm=p Band=15.1… …   Wikipedia

  • transcription factor — Protein required for recognition by RNA polymerases of specific stimulatory sequences in eukaryotic genes. Several are known that activate transcription by RNA polymerase II when bound to upstream promoters. Transcription of the 5S RNA gene in… …   Dictionary of molecular biology

  • transcription factor — noun Date: 1972 any of various proteins that bind to DNA and play a role in the regulation of gene expression by promoting transcription …   New Collegiate Dictionary


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