View source for Transcription factor

{{Transcription factor glossary}}
{{SI}}
{{CMG}}



In the field of [[molecular biology]], a '''transcription factor''' (sometimes called a sequence-specific DNA binding factor) is a [[protein]] that binds to specific parts of [[DNA]] using [[DNA binding domain]]s and is part of the system that controls the transfer (or [[transcription (genetics)|transcription]]) of genetic information from DNA to [[RNA]].<ref name="pmid9570129">{{cite journal | author = Latchman DS | title = Transcription factors: an overview | journal = Int. J. Biochem. Cell Biol. | volume = 29 | issue = 12 | pages = 1305-12 | year = 1997 | pmid = 9570129 | doi = 10.1016/S1357-2725(97)00085-X | issn = }}</ref><ref name="pmid2128034">{{cite journal | author = Karin M | title = Too many transcription factors: positive and negative interactions | journal = New Biol. | volume = 2 | issue = 2 | pages = 126-31 | year = 1990 | pmid = 2128034 | doi = | issn = }}</ref>

Transcription factors perform this function alone, or by using other proteins in a complex, by increasing (as an [[Activator (genetics)|activator]]), or preventing (as a [[repressor]]) the presence of [[RNA polymerase]], a protein which [[transcription (genetics)|transcribes]] genetic information.<ref name="pmid8870495">{{cite journal | author = Roeder RG | title = The role of general initiation factors in transcription by RNA polymerase II | journal = Trends Biochem. Sci. | volume = 21 | issue = 9 | pages = 327-35 | year = 1996 | pmid = 8870495 | doi = 10.1016/0968-0004(96)10050-5 | issn = }}</ref><ref name="pmid8990153">{{cite journal | author = Nikolov DB, Burley SK | title = RNA polymerase II transcription initiation: a structural view | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 94 | issue = 1 | pages = 15-22 | year = 1997 | pmid = 8990153 | doi = 10.1073/pnas.94.1.15 | issn = }}</ref><ref name="pmid11092823">{{cite journal | author = Lee TI, Young RA | title = Transcription of eukaryotic protein-coding genes | journal = Annu. Rev. Genet. | volume = 34 | issue = | pages = 77–137 | year = 2000 | pmid = 11092823 | doi = 10.1146/annurev.genet.34.1.77}}</ref>

==Biological roles==

Transcription factors are one of the groups of proteins that read and interpret the genetic "blueprint" in the DNA.  They bind DNA and help initiate a program of increased or decreased gene transcription.  As such, they are vital for many important cellular processes.  Below are some of the important functions and biological roles transcription factors are involved in:

*  '''Basal transcription regulation'''  In [[eukaryote]]s, an important class of transcription factors called [[general transcription factor]]s (GTFs) are necessary for transcription to occur.  Many of these GTFs don't actually bind DNA but are part of the large transcription [[preinitiation complex]] that interacts with [[RNA polymerase]] directly.  The most common GTFs are [[TFIIA]], [[TFIIB]], [[TFIID]] (see also [[TATA binding protein]]), [[TFIIE]], [[TFIIF]], and [[TFIIH]].

*  '''Development'''  Many transcription factors in [[multicellular organism]]s are involved in development.  Responding to cues (stimuli), these transcription factors turn on/off the transcription of the appropriate genes which in turn allows for changes in cell [[morphology (biology)|morphology]] or activities needed for [[cell fate determination]] and [[cellular differentiation]].  The [[Hox]] transcription factor family, for example, is important for proper [[Regional specification|body pattern formation]] in organisms as diverse as fruit flies to humans.  Another example is the transcription factor encoded by the [[SRY|Sex-determining Region Y]] (SRY) gene which plays a major role in determining gender in humans.

*  '''Response to intercellular signals'''  Cells can communicate with each other by releasing molecules that produce [[signal transduction|signaling cascades]] within another receptive cell.  If the signal requires upregulation or downregulation of genes in the recipient cell, often transcription factors will be downstream in the signaling cascade.  [[Estrogen]] signaling is an example of a fairly short signaling cascade that involves the [[estrogen receptor]] transcription factor:  estrogen is secreted by tissues such as the [[ovary|ovaries]] and [[placenta]], crosses the [[cell membrane]] of the recipient cell, and is bound by the estrogen receptor in the cell's [[cytoplasm]].  The estrogen receptor then goes to the cell's [[nucleus]] and binds to its DNA binding sites, changing the transcriptional regulation of the associated genes.

*  '''Response to environment'''  Not only do transcription factors act downstream of signaling cascades related to biological stimuli, but they can also be downstream of signaling cascades involved in environmental stimuli.  Examples include [[heat shock factor]] (HSF) which upregulates genes necessary for survival at higher temperatures, [[hypoxia inducible factor]] (HIF) which upregulates genes necessary for cell survival in low oxygen environments, and [[sterol regulatory element binding protein]] (SREBP) which helps maintain proper [[lipid]] levels in the cell.  

*  '''Cell cycle control'''  Many transcription factors, especially some that are [[oncogene]]s or [[Tumor suppressor gene|tumor suppressors]], help regulate the cell cycle and as such determine how large a cell will get and when it can divide into two daughter cells.  One example is the [[Myc]] oncogene, which has important roles in [[cell growth]] and [[apoptosis]].

==Regulation of transcription factor activity==

It is common in biology for important processes to have multiple layers of regulation and control.  This is just as true with transcription:  not only do rates of transcription regulate the amounts of gene products (RNA and protein) available to the cell, but the process of transcription itself is regulated.  Below is a brief synopsis of some of the ways that the activity of transcription factors can be regulated:

*  '''Transcription factor synthesis'''  Transcription factors (like all proteins) are transcribed from a gene on a chromosome into RNA, and then the RNA is translated into protein.  Any of these steps can be regulated to affect the production (and thus activity) of a transcription factor.  One interesting implication of this is that transcription factors can regulate themselves.  For example, in a negative feedback loop, the transcription factor acts as its own repressor:  if the transcription factor protein binds the DNA of its own gene, it will down-regulate the production of more of itself.  This is one mechanism to maintain low levels of a transcription factor in a cell.

*  '''Localization to the nucleus'''  In [[eukaryote]]s, transcription factors (like most proteins) are transcribed in the [[nucleus]] but are then translated in the cell's [[cytoplasm]].  Many proteins that are active in the nucleus contain [[nuclear localization signal]]s that direct them to the nucleus.  But for many transcription factors this is a key point in their regulation.  Important classes of transcription factors such as some [[nuclear receptor]]s must first bind a [[ligand]] while in the cytoplasm before they can relocate to the nucleus.

*  '''Activation via chemical modifications or ligand binding'''  Not only is ligand binding able to influence where a transcription factor is located within a cell, but this can also affect whether the transcription factor is in an active state and capable of binding DNA or other cofactors.  Another way that a transcription factor can be activated is by chemical modification of the transcription factor itself.  For example, many transcription factors such as [[STAT protein]]s must be [[phosphorylation|phosphorylated]] before they can bind DNA.

*  '''Accessibility of DNA binding site'''  In eukaryotes, genes that are not being actively transcribed are often located in [[heterochromatin]].  Heterochromatin are regions of chromosomes that are heavily compacted by tightly bundling the DNA onto [[histone]]s and then organizing the histones into compact [[chromatin]] fibers.  DNA within heterochromatin is inaccessible to many transcription factors.  For the transcription factor to bind to its DNA binding site the heterochromatin must be first converted to [[euchromatin]], usually via [[Histone-Modifying Enzymes|histone modifications]].  A transcription factor's DNA binding site may also be inaccessible if the site is already occupied by another transcription factor.  Pairs of transcription factors can play antagonistic roles (activator versus repressor) in the regulation of the same gene.

*  '''Availability of other cofactors/transcription factors needed for a complex'''  Most transcription factors don't work alone.  Often for gene transcription to occur, a number of transcription factors must bind to DNA regulatory sequences.  This collection of transcription factors in turn recruit intermediary proteins such as [[transcription coregulator|cofactor]]s that allow efficient recruitment of the [[preinitiation complex]] and [[RNA polymerase]].  Thus, for a single transcription factor to initiate transcription, all of these other proteins must also be present and the transcription factor must be in a state where it can bind to them if necessary.

[[Image:TATA-binding_protein.png|thumb|200px|left|The transcription factor [[TATA binding protein]] (blue) bound to [[DNA]] (red).  Image by David S. Goodsell based on the [[Protein structure#Protein structure determination|crystal structure]] 1cdw from the Protein Data Bank.]]
<br clear="left"/>
==Structure==

Transcription factors are modular in  structure and contain the following [[protein domains|domains]]:<ref name="pmid9570129" />
* '''DNA-binding domain''' ('''DBD''') which attach to specific sequences of DNA ([[enhancer (genetics)|enhancer]] or [[promoter]] sequences) adjacent to regulated genes.  DNA sequences which bind transcription factors are often referred to as [[hormone response element|'''response elements''']].
* '''Trans-activating domain''' ('''TAD''') which contain binding sites for other proteins such as [[transcription coregulator]]s.  These binding sites are frequently referred to as '''activation functions''' ('''AFs''').<ref name="pmid12893880">{{cite journal | author = Wärnmark A, Treuter E, Wright AP, Gustafsson J-Å | title = Activation functions 1 and 2 of nuclear receptors: molecular strategies for transcriptional activation | journal = Mol. Endocrinol. | volume = 17 | issue = 10 | pages = 1901-9 | year = 2003 | pmid = 12893880 | doi = 10.1210/me.2002-0384 | issn = }}</ref> 
*  An optional '''signal sensing domain''' ('''SSD''') (''e.g.'', a ligand binding domain) which senses external signals and in response transmit these signals to the rest of the transcription complex resulting in up or down regulation of gene expression.  Alternatively the DBD and signal sensing domains may reside on separate proteins that associate within the transcription complex to regulate gene expression.

[[Image:transcription factor schematic.png|thumb|400px|left|Schematic diagram of the amino acid sequence (amino terminus to the left and carboxylic acid terminus to the right) of a prototypical transcription factor which contains (1) a DNA-binding domain ('''DBD'''), (2) signal sensing domain ('''SSD'''), and a transactivation domain ('''TAD''').  The order of placement and the number of domains may differ in various types of transcription factors.  In addition, the transactivation and signal sensing functions are frequently contained within the same domain.]]
<br clear="left"/>

==DNA binding domains==

The portion ([[protein domains|domain]]) of the transcription factor that binds DNA is called its DNA binding domain.  Below is a partial list of some of the major families of DNA-binding domains/transcription factors:

*	[[lambda phage#Repressor|lambda repressor]]-like ({{SCOP|47413}}) ({{InterPro|IPR010982}})
*	C-terminal effector domain of the bipartite response regulators ({{SCOP|46894}}) ({{InterPro|IPR001789}})
*	srf-like (serum response factor) ({{SCOP|55455}}) ({{InterPro|IPR002100}})
*	[[basic-helix-loop-helix]] ({{SCOP|47460}}) ({{InterPro|IPR001092}})
*	GCC box ({{SCOP|54175}})
*	Zn<sub>2</sub>/Cys<sub>6</sub> ({{SCOP|57701}})
*	[[winged helix]] ({{SCOP|46785}}) ({{InterPro|IPR011991}})
*	Zn<sub>2</sub>/Cys<sub>8</sub> [[nuclear receptor]] zinc finger ({{SCOP|57716}})  ({{InterPro|IPR001628}})
*	[[homeodomain fold|homeodomain proteins]] - bind to [[homeobox]] DNA sequences which in turn encode other transcription factors.  Homeodomain proteins play critical roles in the regulation of [[developmental biology|development]].  ({{SCOP|46689}}) ({{InterPro|IPR009057}})
*	multi-domain Cys<sub>2</sub>His<sub>2</sub> zinc fingers ({{SCOP|57667}}) ({{InterPro|IPR007087}})
*	basic-leucine zipper (bZIP) ({{SCOP|57959}}) ({{InterPro|IPR004827}})

There are other proteins that play crucial roles in the regulation of transcription, that aren't classified as transcription factors because they lack [[DNA binding domain]]s.<ref name="pmid11823631">{{cite journal | author = Brivanlou AH, Darnell JE | title = Signal transduction and the control of gene expression | journal = Science | volume = 295 | issue = 5556 | pages = 813-8 | year = 2002 | pmid = 11823631 | doi = 10.1126/science.1066355 | issn = }}</ref> (for example [[coactivator (genetics)|coactivator]]s, [[Chromatin Structure Remodeling (RSC) Complex|chromatin remodeler]]s, [[histone acetyltransferase|histone acetylases]], [[histone deacetylase| deacetylases]], [[kinase]]s, and [[methylase]]s).

==Transcription factor binding sites/response elements==

The DNA sequence that a transcription factor binds to is called a transcription factor binding site or response element.  

Chemically, transcription factors usually interact with their binding sites using a combination of [[hydrogen bond]]s and [[Van der Waals force]]s.  Due to the nature of these chemical interactions, most transcription factors bind DNA in a sequence specific manner.  However, not all [[Base pair|bases]] in the transcription factor binding site may actually interact with the transcription factor.  In addition some of these interactions may be weaker than others.  Thus, transcription factors don't bind just one sequence but are capable of binding a subset of closely related sequences, each with a different strength of interaction.  

For example, although the [[consensus sequence|consensus binding site]] for the [[TATA binding protein]] (TBP) is:

TATAAAA

the TBP transcription factor can also bind similar sequences such as:

TATATAT  or  TATATAA

Because transcription factors can bind a set of related sequences and the sequences don't tend to be that long, potential transcription factor binding sites can occur just by chance if the DNA sequence is long enough.  It is unlikely, however, that a transcription factor binds all compatible sequences in the [[genome]] of the [[cell (biology)|cell]].  Other constraints, such as DNA accessibility in the cell or availability of [[cofactor]]s may also help dictate where a transcription factor will actually bind.  Thus, given the genome sequence it is still difficult to predict where a transcription factor will actually bind in a living cell.

==Classes==
===Mechanistic===

There are three mechanistic classes of transcription factors:

*[[General transcription factor]]s are involved in the formation of a [[preinitiation complex]]. The most common are abbreviated as [[TFIIA]], [[TFIIB]], [[TFIID]], [[TFIIE]], [[TFIIF]], and [[TFIIH]]. They are ubiquitous and interact with the core promoter region surrounding the transcription start site(s) of all [[class II gene]]s.<ref name="pmidc">{{cite journal | author = Orphanides G, Lagrange T, Reinberg D | title = The general transcription factors of RNA polymerase II | journal = Genes Dev. | volume = 10 | issue = 21 | pages = 2657-83 | year = 1996 | pmid = 8946909 | doi = 10.1101/gad.10.21.2657 | issn = }}</ref>
*'''Upstream transcription factors''' are proteins that bind somewhere upstream of the initiation site to stimulate or repress transcription.
*'''Inducible transcription factors''' are similar to upstream transcription factors but require activation or inhibition.

===Functional===

Transcription factors have been classified according to their regulatory function:<ref name="pmid11823631" />

* I. '''constitutively-active''' - present in all cells at all times - [[general transcription factor]]s, [[Sp1]], [[NF1]], [[Ccaat-enhancer-binding proteins|CCAAT]]
* II. '''conditionally-active''' - requires activation
** II.A '''developmental''' (cell specific) - expression is tightly controlled, but, once expressed, require no additional activation - [[GATA transcription factor|GATA]], [[hepatocyte nuclear factors|HNF]], [[PIT-1]], [[MyoD]], [[Myf5]], [[Hox]], [[winged-helix transcription factors|Winged Helix]]
** II.B '''signal-dependent''' - requires external signal for activation
*** II.B.1 '''extracellular ligand-dependent''' - [[nuclear receptor]]s
*** II.B.2 '''intracellular ligand-dependent''' - activated by small intracellular molecules - [[Sterol regulatory element-binding protein|SREBP]], [[p53]], orphan nuclear receptors
*** II.B.3 '''cell membrane receptor-dependent'''- second messenger signaling cascades resulting in the phosphorylation of the transcription factor
**** II.B.3.a '''resident nuclear factors'''  - reside in the nucleus regardless of activation state -   [[CREB]], [[AP-1 (transcription factor)|AP-1]], [[Mef2]]
**** II.B.3.b '''latent cytoplasmic factors''' - inactive form reside in the cytoplasm, but, when activated, are translocated into the nucleus -  [[STAT protein|STAT]], [[R-SMAD]], [[NF-kB]], [[Notch signaling|Notch]], [[Tubby protein|TUBBY]], [[NFAT]]

==Roles and Conservation in Different Organisms==

Transcription factors are essential for the regulation of gene expression and consequently are found in all living organisms. The number of transcription factors found within an organism increases with the genome size and the larger genomes tend to have more transcription factors per gene.<ref name="pmid12957540">{{cite journal | author = van Nimwegen E | title = Scaling laws in the functional content of genomes | journal = Trends Genet. | volume = 19 | issue = 9 | pages = 479-84 | year = 2003 | pmid = 12957540 | doi = 10.1016/S0168-9525(03)00203-8 | issn = }}</ref>

There are approximately 2600 proteins in the [[human genome]] that contain DNA-binding domains and most of these are presumed to function as transcription factors.<ref name="pmid15193307">{{cite journal | author = Babu MM, Luscombe NM, Aravind L, Gerstein M, Teichmann SA | title = Structure and evolution of transcriptional regulatory networks | journal = Curr. Opin. Struct. Biol. | volume = 14 | issue = 3 | pages = 283-91 | year = 2004 | pmid = 15193307 | doi = 10.1016/j.sbi.2004.05.004 | issn = }}</ref>  Therefore approximately 10% of genes in the genome code for transcription factors which makes this family the single largest family of human proteins.  Furthermore genes are often flanked by several binding sites for distinct transcription factors and efficient expression of each these genes requires the cooperative action of several different transcription factors (see for example [[hepatocyte nuclear factors#Function|hepatocyte nuclear factors]]).  Hence the combinatorial use of a subset of the approximately 2000 human transcription factors easily accounts for the unique regulation of each gene in the human genome during [[developmental biology|development]].<ref name="pmid11823631" />

==Transcription factors and human disease==
Due to their important roles in development, intercellular signaling, and cell cycle, some human diseases have been associated with [[mutation]]s in transcription factors.  Below are a few of the more well-studied examples:

*  '''Rett syndrome'''  Mutations in the [[MECP2]] transcription factor are associated with [[Rett syndrome]], a neurodevelopmental disorder.

*  '''Diabetes'''  A rare form of [[diabetes]] called MODY (Maturity onset diabetes of the young) can be caused by mutations in [[hepatocyte nuclear factors]] (HNFs) or insulin promoter factor-1 (IPF1).   

*  '''Developmental verbal dyspraxia'''  Mutations in the [[FOXP2]] transcription factor are associated with [[developmental dyspraxia|developmental verbal dyspraxia]], a disease in which individuals are unable to produce the finely coordinated movements required for speech.   

*  '''Autoimmune diseases'''  Mutations in the [[FOXP3]] transcription factor cause a rare form of [[autoimmune disease]] called [[IPEX]].

*  '''Cancer'''  Many transcription factors are tumor suppressors or oncogenes, and thus mutations or aberrant regulation of them are associated with cancer.  For example, [[Li-Fraumeni syndrome]] is caused by mutations in the tumor suppressor [[p53 (protein)|p53]].

==Classification of transcription factors==

Transcription factors are often classified based on the similarity of their DNA binding domains:<ref name="pmid15706513">{{cite journal | author = Stegmaier P, Kel AE, Wingender E | title = Systematic DNA-binding domain classification of transcription factors | journal = Genome informatics. International Conference on Genome Informatics | volume = 15 | issue = 2 | pages = 276-86 | year = 2004 | pmid = 15706513 | doi = | issn = | url = http://www.jsbi.org/journal/GIW04/GIW04F028.html }}</ref><ref>PMID 16381825</ref><ref>{{cite web|title=TRANSFAC<sup>®</sup> database|url=http://www.gene-regulation.com/pub/databases/transfac/cl.html|accessdate = 2007-08-05}}</ref>

*1 Superclass: Basic Domains ([[Basic-helix-loop-helix]])
**1.1 Class: [[Leucine zipper]] factors ([[bZIP]])
***1.1.1 Family: [[AP-1 (transcription factor)|AP-1]](-like) components; includes ([[c-Fos]]/[[c-Jun]])
***1.1.2 Family: [[CREB]]
***1.1.3 Family: [[Ccaat-enhancer-binding proteins|C/EBP]]-like factors
***1.1.4 Family: bZIP / [[PAR (transcription factor)|PAR]]
***1.1.5 Family: Plant G-box binding factors
***1.1.6 Family: ZIP only
**1.2 Class: Helix-loop-helix factors ([[bHLH]])
***1.2.1 Family: Ubiquitous (class A) factors
***1.2.2 Family: Myogenic transcription factors ([[MyoD]])
***1.2.3 Family: Achaete-Scute
***1.2.4 Family: Tal/Twist/Atonal/Hen
**1.3 Class: Helix-loop-helix / leucine zipper factors ([[basic helix-loop-helix leucine zipper transcription factors|bHLH-ZIP]])
***1.3.1 Family: Ubiquitous bHLH-ZIP factors; includes USF  ({{gene|USF1}}, {{gene|USF2}}); SREBP ([[Sterol regulatory element binding protein|SREBP]])
***1.3.2 Family: Cell-cycle controlling factors; includes [[Myc|c-Myc]]
**1.4 Class: NF-1
***1.4.1 Family: NF-1 ({{gene|NFIC}})
**1.5 Class: RF-X
***1.5.1 Family: RF-X ({{gene|NFX2}}, {{gene|NFX3}}, {{gene|NFX5}})
**1.6 Class: bHSH

*2 Superclass: Zinc-coordinating DNA-binding domains
**2.1 Class: Cys4 [[zinc finger]] of [[nuclear receptor]] type
***2.1.1 Family: [[Steroid hormone receptor]]s
***2.1.2 Family: [[Thyroid hormone receptor]]-like factors
**2.2 Class: diverse Cys4 zinc fingers
***2.2.1 Family: [[GATA transcription factor|GATA-Factors]]
**2.3 Class: Cys2His2 zinc finger domain
***2.3.1 Family: Ubiquitous factors, includes [[TFIIIA]], [[Sp1]]
***2.3.2 Family: Developmental / cell cycle regulators; includes [[Krüppel]]
***2.3.4 Family: Large factors with NF-6B-like binding properties
**2.4 Class: Cys6 cysteine-zinc cluster
**2.5 Class: Zinc fingers of alternating composition

*3 Superclass: [[Helix-turn-helix]]
**3.1 Class: [[Homeobox|Homeo domain]]
***3.1.1 Family: Homeo domain only; includes [[Ubx]]
***3.1.2 Family: [[POU family|POU domain]] factors; includes [[Octamer transcription factor|Oct]]
***3.1.3 Family: Homeo domain with LIM region
***3.1.4 Family: homeo domain plus zinc finger motifs
**3.2 Class: Paired box
***3.2.1 Family: Paired plus homeo domain
***3.2.2 Family: Paired domain only
**3.3 Class: [[FOX proteins|Fork head]] / [[Winged-helix transcription factors|winged helix]]
***3.3.1 Family: Developmental regulators; includes [[forkhead]]
***3.3.2 Family: Tissue-specific regulators
***3.3.3 Family: Cell-cycle controlling factors
***3.3.0 Family: Other regulators
**3.4 Class: [[Heat Shock Factor]]s
***3.4.1 Family: HSF
**3.5 Class: Tryptophan clusters
***3.5.1 Family: Myb
***3.5.2 Family: Ets-type
***3.5.3 Family: [[Interferon regulatory factors]]
**3.6 Class: TEA domain
***3.6.1 Family: TEA ({{gene|TEAD1}}, {{gene|TEAD2}}, {{gene|TEAD3}}, {{gene|TEAD4}})

*4 Superclass: beta-Scaffold Factors with Minor Groove Contacts
**4.1 Class: RHR (Rel homology region)
***4.1.1 Family: Rel/[[Ankyrin repeat|ankyrin]]; [[NF-kB|NF-kappaB]]
***4.1.2 Family: ankyrin only
***4.1.3 Family: NF-AT ({{gene|NFATC1}}, {{gene|NFATC2}}, {{gene|NFATC3}})
**4.2 Class: STAT
***4.2.1 Family: [[STAT protein|STAT]]
**4.3 Class: p53
***4.3.1 Family: [[p53]]
**4.4 Class: [[MADS-box|MADS box]]
***4.4.1 Family: Regulators of differentiation; includes ([[Mef2]])
****4.4.2 Family: Responders to external signals, SRF (serum response factor)  ({{gene|SRF}})
**4.5 Class: beta-Barrel alpha-helix transcription factors
**4.6 Class: [[TATA binding protein]]s
***4.6.1 Family: TBP
***4.7.1 Family: [[SOX genes]], [[SRY]]
***4.7.2 Family: TCF-1 ({{gene|TCF1}})
***4.7.3 Family: HMG2-related, SSRP1 ({{gene|SSRP1}})
***4.7.5 Family: MATA
**4.8 Class: Heteromeric CCAAT factors
***4.8.1 Family: Heteromeric CCAAT factors
**4.9 Class: Grainyhead
***4.9.1 Family: Grainyhead
**4.10 Class: Cold-shock domain factors
***4.10.1 Family: csd
**4.11 Class: Runt
***4.11.1 Family: Runt

*0 Superclass: Other Transcription Factors
**0.1 Class: Copper fist proteins
**0.2 Class: HMGI(Y) ({{gene|HMGA1}})
***0.2.1 Family: HMGI(Y)
**0.3 Class: Pocket domain
**0.4 Class: E1A-like factors
**0.5 Class: [[Apetala 2|AP-2]]/EREBP-related factors

== References ==
{{Reflist|2}}

== See also ==
<div style="-moz-column-count:1; column-count:1;">
* [[DNA-binding protein]]
* [[Nuclear receptor]], a class of ligand activated transcription factors
</div>

==External links==
* [http://transcriptionfactor.org/ DBD database of predicted transcription factors]<ref name="pmid16381970">{{cite journal | author = Kummerfeld SK, Teichmann SA. | title = DBD: a transcription factor prediction database | journal = Nucleic Acids Res. | volume = 34 | issue = Database issue | pages = D74-81 | year = 2006 | pmid = 16381825 | doi = 10.1093/nar/gkj131 }}</ref> Uses a curated set of DNA-binding domains to predict transcription factors in all completely sequenced genomes
* [http://8e.devbio.com/article.php?ch=5&id=39 Transcription factors: DevBio on-line supplementary material to ''Developmental Biology'' by Scott F. Gilbert]<ref name="isbn0-87893-250-X">{{cite book | author = Singer, Susan R.; Gilbert, Scott F. | title = Developmental Biology | publisher = Sinauer Associates | location = Sunderland, Mass | year = 2006 | pages = | isbn = 0-87893-250-X | oclc = | doi = }}</ref>
* [http://www.gene-regulation.com/pub/databases/transfac/cl.html A classification of transcription factors based on their DNA-binding domains]<ref name="pmid16381825">{{cite journal | author = Matys V, Kel-Margoulis OV, Fricke E, Liebich I, Land S, Barre-Dirrie A, Reuter I, Chekmenev D, Krull M, Hornischer K, Voss N, Stegmaier P, Lewicki-Potapov B, Saxel H, Kel AE, Wingender E | title = TRANSFAC<sup>®</sup> and its module TRANSCompel:<sup>®</sup> transcriptional gene regulation in eukaryotes | journal = Nucleic Acids Res. | volume = 34 | issue = Database issue | pages = D108-10 | year = 2006 | pmid = 16381825 | doi = 10.1093/nar/gkj143 | issn = }}</ref>
* {{MeshName|Transcription+Factors}}

{{Cell_signaling}}
{{Transcription factors}}

[[Category:Gene expression]]
[[Category:Transcription factors]]
[[Category:Hematology]]

[[de:Transkriptionsfaktor]]
[[es:Factor de transcripción]]
[[fr:Facteur de transcription]]
[[it:Fattore di trascrizione]]
[[he:גורם שעתוק]]
[[ja:転写因子]]
[[pl:Czynnik transkrypcyjny]]
[[pt:Fator de transcrição]]
[[ru:Активатор (ферменты)]]
[[sl:Transkripcijski faktor]]
[[fi:Transkriptiofaktori]]
[[sv:Transkriptionsfaktor]]
[[zh:转录因子]]

{{WH}}
{{WS}}