Transcription factor facts for kids

Transcription factors help to regulate genes. Each transcription factor binds to a specific DNA sequence. That is how they control the rate of transcription of genetic information from DNA to messenger RNA.

A transcription factor is sometimes called a 'sequence-specific DNA-binding factor'. Alone or with other proteins, they promote or block RNA polymerase. RNA polymerase is the enzyme that copies genetic information from DNA to RNA for specific genes.

Transcription factors have one or more DNA-binding domains (DBDs). These attach to sequences of DNA next to the genes they regulate. Other proteins (such as coactivators, chromatin remodellers, histone acetylases or deacetylases, kinases, and methylases) also play crucial roles in gene regulation. Because they lack DNA-binding domains, they are not called transcription factors.

Illustration of an activator

Glossary:

• gene expression – the process by which information from a gene is used in the synthesis of a functional gene product such as a protein
• transcription – the process of making messenger RNA (mRNA) from a DNA template by RNA polymerase
• transcription factor – a protein that binds to DNA and regulates gene expression by promoting or suppressing transcription
• 'transcriptional regulation' – controlling the rate of gene transcription for example by helping or hindering RNA polymerase binding to DNA
• 'upregulation', activation or promotion – increase the rate of gene transcription
• 'downregulation', repression or suppression – decrease the rate of gene transcription
• 'coactivator' – a protein that works with transcription factors to increase the rate of gene transcription
• 'corepressor' – a protein that works with transcription factors to decrease the rate of gene transcription
• 'response element' – a sequence of DNA to which a transcription factor binds

Images for kids

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  Schematic diagram of the amino acid sequence (amino terminus to the left and carboxylic acid terminus to the right) of a prototypical transcription factor that contains (1) a DNA-binding domain (DBD), (2) signal-sensing domain (SSD), and Activation domain (AD). 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.

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  Domain architecture example: Lactose Repressor (LacI). The N-terminal DNA binding domain (labeled) of the lac repressor binds its target DNA sequence (gold) in the major groove using a helix-turn-helix motif. Effector molecule binding (green) occurs in the core domain (labeled), a signal sensing domain. This triggers an allosteric response mediated by the linker region (labeled).