Selective factor 1 (also known as SL1) is a transcription factor that binds to the promoter of genes and recruits a preinitiation complex to which RNA polymerase I will bind to and begin the transcription of ribosomal RNA (rRNA). [1] [2]
Selective factor 1 (also known as SL1) is a transcription factor that binds to the promoter of genes and recruits a preinitiation complex to which RNA polymerase I will bind to and begin the transcription of ribosomal RNA (rRNA). [1] [2]
SL1 was discovered by Robert Tjian and his colleagues in 1985 when they separated a HeLa cell extract into two functional fractions. [3] One factor has RNA polymerase I activity, but no ability to initiate accurate transcription of a human rRNA template. This transcription factor, SL1, showed species specificity. [4] That is, it could distinguish between the human and mouse rRNA promoter, [5] and added increasing amount of human template at the expense of the mice template. [6] Tijian and coworkers went on to show that by footprinting a partially purified polymerase 1 preparation could bind to the human rRNA promoter. In particular it causes a footprint over a region of the UCE called A site. [7] This binding is not due to polymerase I itself but to a transcription factor called upstream binding factor, UBF.
SLI functions in assembling the transcription preinitiation complex. It is also a major determinant of species-specificity in ribosomal RNA gene transcription. Research suggests that UBF and SL1 act synergistically to stimulate transcription. Recent investigation also suggests that SL1 is a target for cancer therapy. [8]
SL1 is composed of the TATA-binding protein and three TAF (TATA box-binding protein-associated factor) subunits (TAF1A, TAF1B, and TAF1C). [9] It is therefore possible to inhibit SL1 activity with anti-TBP antibodies.
In molecular biology, the TATA box is a sequence of DNA found in the core promoter region of genes in archaea and eukaryotes. The bacterial homolog of the TATA box is called the Pribnow box which has a shorter consensus sequence.
The preinitiation complex is a complex of approximately 100 proteins that is necessary for the transcription of protein-coding genes in eukaryotes and archaea. The preinitiation complex positions RNA polymerase II at gene transcription start sites, denatures the DNA, and positions the DNA in the RNA polymerase II active site for transcription.
RNA polymerase 1 is, in higher eukaryotes, the polymerase that only transcribes ribosomal RNA, a type of RNA that accounts for over 50% of the total RNA synthesized in a cell.
General transcription factors (GTFs), also known as basal transcriptional factors, are a class of protein transcription factors that bind to specific sites (promoter) on DNA to activate transcription of genetic information from DNA to messenger RNA. GTFs, RNA polymerase, and the mediator constitute the basic transcriptional apparatus that first bind to the promoter, then start transcription. GTFs are also intimately involved in the process of gene regulation, and most are required for life.
The TATA-binding protein (TBP) is a general transcription factor that binds specifically to a DNA sequence called the TATA box. This DNA sequence is found about 30 base pairs upstream of the transcription start site in some eukaryotic gene promoters.
Transcription factor II D (TFIID) is one of several general transcription factors that make up the RNA polymerase II preinitiation complex. RNA polymerase II holoenzyme is a form of eukaryotic RNA polymerase II that is recruited to the promoters of protein-coding genes in living cells. It consists of RNA polymerase II, a subset of general transcription factors, and regulatory proteins known as SRB proteins. Before the start of transcription, the transcription Factor II D (TFIID) complex binds to the core promoter DNA of the gene through specific recognition of promoter sequence motifs, including the TATA box, Initiator, Downstream Promoter, Motif Ten, or Downstream Regulatory elements.
Transcription initiation factor TFIID subunit 6 is a protein that in humans is encoded by the TAF6 gene.
Transcription initiation factor TFIID subunit 7 also known as TAFII55 is a protein that in humans is encoded by the TAF7 gene.
Transcription initiation factor TFIID subunit 1, also known as transcription initiation factor TFIID 250 kDa subunit (TAFII-250) or TBP-associated factor 250 kDa (p250), is a protein that in humans is encoded by the TAF1 gene.
Upstream binding transcription factor (UBTF), or upstream binding factor (UBF), is a protein that in humans is encoded by the UBTF gene.
Transcription initiation factor TFIID subunit 2 is a protein that in humans is encoded by the TAF2 gene.
Transcription initiation factor TFIID subunit 5 is a protein that in humans is encoded by the TAF5 gene.
TATA-binding protein-associated factor 172 is a protein that in humans is encoded by the BTAF1 gene.
Transcription initiation factor TFIID subunit 13 is a protein that in humans is encoded by the TAF13 gene.
TATA box-binding protein-associated factor RNA polymerase I subunit C is an enzyme that in humans is encoded by the TAF1C gene.
TATA box-binding protein-associated factor RNA polymerase I subunit A is an enzyme that in humans is encoded by the TAF1A gene.
TATA box-binding protein-associated factor RNA polymerase I subunit B is an enzyme that in humans is encoded by the TAF1B gene.
RNA polymerase II holoenzyme is a form of eukaryotic RNA polymerase II that is recruited to the promoters of protein-coding genes in living cells. It consists of RNA polymerase II, a subset of general transcription factors, and regulatory proteins known as SRB proteins.
The TBP-associated factors (TAF) are proteins that associate with the TATA-binding protein in transcription initiation. It is a part of the transcription initiation factor TFIID multimeric protein complex. It also makes up many other factors, including SL1. They mediate the formation of the transcription preinitiation complex, a step preceding transcription of DNA to RNA by RNA polymerase II.
Archaeal transcription factor B is a protein family of extrinsic transcription factors that guide the initiation of RNA transcription in organisms that fall under the domain of Archaea. It is homologous to eukaryotic TFIIB and, more distantly, to bacterial sigma factor. Like these proteins, it is involved in forming transcription preinitiation complexes. Its structure includes several conserved motifs which interact with DNA and other transcription factors, notably the single type of RNA polymerase that performs transcription in Archaea.