General transcription factor
Encyclopedia
General transcription factors (GTF's) or basal transcription factors are protein
transcription factor
s that have been shown to be important in the transcription
of class II gene
s to mRNA templates. Many of them are involved in the formation of a preinitiation complex
, which, together with RNA polymerase II
, bind to and read the single-stranded DNA gene template.
, (TBP) is a GTF that binds to the TATAA box (T=Thymine
, A=Adenine
) the motif of nucleic acids that is directly upstream from the coding region in many genes. TBP is responsible for the recruitment of the RNA Pol II holoenzyme, the final event in transcription initiation. These proteins are ubiquitous and interact with the core promoter region of DNA, which contains the transcription start site(s) of all class II genes.
Not all GTFs play a role in transcriptional initiation; some are required for the second general step in transcription, elongation. For example, members of the FACT
complex (Spt16/Pob3 in S. cerevisiae, SUPT16H/SSRP1 in humans) facilitate the rapid movement of RNA Pol II over the encoding region of genes. This is accomplished by moving the histone
octamer out of the way of an active polymerase and thereby decondensing the chromatin.
Note: Basal transcription in test tubes has been achieved using only highly-purified recombinant TFIIB and TFIIF.
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
transcription factor
Transcription factor
In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...
s that have been shown to be important in the transcription
Transcription (genetics)
Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...
of class II gene
Class II gene
A class II gene is a type of gene that codes for a protein. Class II genes are transcribed by RNAP II.Class II genes have a promoter that often contains a TATA box.Basal transcription of class II genes requires the formation of a preinitiation complex....
s to mRNA templates. Many of them are involved in the formation of a preinitiation complex
Preinitiation complex
The preinitiation complex is a large complex of proteins that is necessary for the transcription of protein-coding genes in eukaryotes...
, which, together with RNA polymerase II
RNA polymerase II
RNA polymerase II is an enzyme found in eukaryotic cells. It catalyzes the transcription of DNA to synthesize precursors of mRNA and most snRNA and microRNA. A 550 kDa complex of 12 subunits, RNAP II is the most studied type of RNA polymerase...
, bind to and read the single-stranded DNA gene template.
Functions
GTFs are intimately involved in the process of gene regulation, and most are required for life. TATA binding proteinTATA Binding Protein
The TATA-binding protein is a general transcription factor that binds specifically to a DNA sequence called the TATA box. This DNA sequence is found about 35 base pairs upstream of the transcription start site in some eukaryotic gene promoters...
, (TBP) is a GTF that binds to the TATAA box (T=Thymine
Thymine
Thymine is one of the four nucleobases in the nucleic acid of DNA that are represented by the letters G–C–A–T. The others are adenine, guanine, and cytosine. Thymine is also known as 5-methyluracil, a pyrimidine nucleobase. As the name suggests, thymine may be derived by methylation of uracil at...
, A=Adenine
Adenine
Adenine is a nucleobase with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate and the cofactors nicotinamide adenine dinucleotide and flavin adenine dinucleotide , and protein synthesis, as a chemical component of DNA...
) the motif of nucleic acids that is directly upstream from the coding region in many genes. TBP is responsible for the recruitment of the RNA Pol II holoenzyme, the final event in transcription initiation. These proteins are ubiquitous and interact with the core promoter region of DNA, which contains the transcription start site(s) of all class II genes.
Not all GTFs play a role in transcriptional initiation; some are required for the second general step in transcription, elongation. For example, members of the FACT
FACT (biology)
FACT is a heterodimeric protein complex that affects eukaryotic RNA polymerase II transcription elongation both in vitro and in vivo...
complex (Spt16/Pob3 in S. cerevisiae, SUPT16H/SSRP1 in humans) facilitate the rapid movement of RNA Pol II over the encoding region of genes. This is accomplished by moving the histone
Histone
In biology, histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes. They are the chief protein components of chromatin, acting as spools around which DNA winds, and play a role in gene regulation...
octamer out of the way of an active polymerase and thereby decondensing the chromatin.
Types
The general transcription factors that are required for transcription by RNA polymerase II in vitro are:- TFIIA (see TFIIA; TFIIA is not a real basal transcription factor.)
- TFIIB (see TFIIB)
- TFIID (see TFIID and TATA binding proteinTATA Binding ProteinThe TATA-binding protein is a general transcription factor that binds specifically to a DNA sequence called the TATA box. This DNA sequence is found about 35 base pairs upstream of the transcription start site in some eukaryotic gene promoters...
) - TFIIE (see TFIIE)
- TFIIF (see TFIIF)
- TFIIH (see TFIIH)
Note: Basal transcription in test tubes has been achieved using only highly-purified recombinant TFIIB and TFIIF.
See also
- RNA polymerase IIRNA polymerase IIRNA polymerase II is an enzyme found in eukaryotic cells. It catalyzes the transcription of DNA to synthesize precursors of mRNA and most snRNA and microRNA. A 550 kDa complex of 12 subunits, RNAP II is the most studied type of RNA polymerase...
for simpler explanation on transcription factors - Nuclear receptorNuclear receptorIn the field of molecular biology, nuclear receptors are a class of proteins found within cells that are responsible for sensing steroid and thyroid hormones and certain other molecules...
, an important class of transcription factors
External links
- http://www.yeastgenome.org has highly detailed information on most known GTF's and is an excellent resource for students and researchers alike
- Descriptive images of GTF assembly
