transcription factor

(noun)

a protein that binds to specific DNA sequences, thereby controlling the flow (or transcription) of genetic information from DNA to mRNA

Related Terms

Examples of transcription factor in the following topics:

  • The Promoter and the Transcription Machinery

    • The purpose of the promoter is to bind transcription factors that control the initiation of transcription.
    • To initiate transcription, a transcription factor (TFIID) is the first to bind to the TATA box.
    • In addition to the general transcription factors, other transcription factors can bind to the promoter to regulate gene transcription.
    • The region that a particular transcription factor binds to is called the transcription factor binding site.
    • Transcription factors recognize the promoter.

  • Cancer and Transcriptional Control

    • Mutations that activate transcription factors, such as increased phosphorylation, can increase the binding of a transcription factor to its binding site in a promoter.
    • Alternatively, a mutation in the DNA of a promoter or enhancer region can increase the binding ability of a transcription factor.
    • Identifying how a transcription factor binds, or a pathway that activates where a gene can be turned off, has led to new drugs and new ways to treat cancer.
    • This can lead to increased phosphorylation of key transcription factors that increase transcription.
    • The EGFR pathway activates many protein kinases that, in turn, activate many transcription factors that control genes involved in cell growth.

  • Initiation of Transcription in Eukaryotes

    • Initiation is the first step of eukaryotic transcription and requires RNAP and several transcription factors to proceed.
    • The completed assembly of transcription factors and RNA polymerase bind to the promoter, forming a transcription pre-initiation complex (PIC).
    • The TATA box, as a core promoter element, is the binding site for a transcription factor known as TATA-binding protein (TBP), which is itself a subunit of another transcription factor: Transcription Factor II D (TFIID).
    • One transcription factor, Transcription Factor II H (TFIIH), is involved in separating opposing strands of double-stranded DNA to provide the RNA Polymerase access to a single-stranded DNA template.
    • Transcription factors recognize the promoter, RNA polymerase II then binds and forms the transcription initiation complex.

  • Transcriptional Enhancers and Repressors

    • Enhancer regions are binding sequences, or sites, for transcription factors.
    • This shape change allows the interaction between the activators bound to the enhancers and the transcription factors bound to the promoter region and the RNA polymerase to occur.
    • Like the transcriptional activators, repressors respond to external stimuli to prevent the binding of activating transcription factors.
    • A corepressor is a protein that decreases gene expression by binding to a transcription factor that contains a DNA-binding domain.
    • Activators bound to the distal control elements interact with mediator proteins and transcription factors.

  • Regulation of Sigma Factor Activity

    • Sigma factors are proteins that function in transcription initiation .
    • Sigma factor synthesis is controlled at the levels of both transcription and translation.
    • If transcription of genes involved in growth is necessary, the sigma factors will be translated to allow for transcription initiation to occur.
    • However, if transcription of genes is not required, sigma factors will not be active.
    • The anti-sigma factors are responsible for regulating inhibition of transcriptional activity in organisms that require sigma factor for proper transcription initiation.

  • Control of Transcription in Archaea

    • Transcription and translation in archaea resemble these processes in eukaryotes more than in bacteria.
    • The proteins that archaea, bacteria and eukaryotes share form a common core of cell function, relating mostly to transcription, translation, and nucleotide metabolism.
    • Transcription and translation in archaea resemble these processes in eukaryotes more than in bacteria, with the archaean RNA polymerase and ribosomes being very close to their equivalents in eukaryotes.
    • Although archaea only have one type of RNA polymerase, its structure and function in transcription seems to be close to that of the eukaryotic RNA polymerase II, with similar protein assemblies (the general transcription factors) directing the binding of the RNA polymerase to a gene's promoter.
    • However, other archaean transcription factors are closer to those found in bacteria.

  • Prokaryotic Transcription and Translation Are Coupled

    • Many of these transcription factors are homodimers containing helix-turn-helix DNA-binding motifs.
    • The RNA polymerase transcribes the DNA (the beta subunit initiates the synthesis), but produces about 10 abortive (short, non-productive) transcripts which are unable to leave the RNA polymerase because the exit channel is blocked by the σ-factor.The σ-factor eventually dissociates from the holoenzyme, and elongation proceeds.
    • Additional transcription regulation comes from transcription factors that can affect the stability of the holoenzyme structure at initiation.
    • Rho-dependent termination uses a termination factor called ρ factor(rho factor) which is a protein to stop RNA synthesis at specific sites.
    • A stem loop structure upstream of the terminator region pauses the RNAP, when ρ-factor reaches the RNAP, it causes RNAP to dissociate from the DNA, terminating transcription.

  • Prokaryotic versus Eukaryotic Gene Expression

    • When the resulting protein is no longer needed, transcription stops.
    • When more protein is required, more transcription occurs.
    • The processes of transcription and translation are physically separated by the nuclear membrane; transcription occurs only within the nucleus, and translation occurs only outside the nucleus within the cytoplasm.
    • Regulation may occur when the DNA is uncoiled and loosened from nucleosomes to bind transcription factors (epigenetics), when the RNA is transcribed (transcriptional level), when the RNA is processed and exported to the cytoplasm after it is transcribed (post-transcriptional level), when the RNA is translated into protein (translational level), or after the protein has been made (post-translational level).
    • Prokaryotic transcription and translation occur simultaneously in the cytoplasm, and regulation occurs at the transcriptional level.

  • Regulation of Sigma Factor Translation

    • Sigma factors are groups of proteins that regulate transcription and therefore function in house-keeping, metabolic, and regulation of growth processes in bacteria.
    • The regulation of expression of sigma factors occurs at transcriptional, translational, and post-translational levels as dictated by the cellular environment and the presence or absence of numerous cofactors.
    • Sigma factors include numerous types of factors.
    • Specifically, the translational control of the sigma factor is a major level of control.
    • Using RpoS proteins as the focus, the RpoS expression and transcription is regulated at the translational level.

  • Slipped-Strand Mispairing

    • Transcriptional regulation occurs in several ways .
    • Through SSM the TA repeat region can undergo addition or subtraction of TA dinucleotides which results in the reversible ON phase or OFF phase of transcription of the hifA and hifB.
    • The second way that SSM induces transcriptional regulation is by changing the short repeat sequences located outside the promoter.
    • It can also lead to differences in post-transcriptional stability of mRNA.
    • Purple ovals can either be a transcription factor (TF) or RNA polymerase (RNAP).