promoter

(noun)

the section of DNA that controls the initiation of RNA transcription

Related Terms

Examples of promoter in the following topics:

  • The Promoter and the Transcription Machinery

    • The promoter region is immediately upstream of the coding sequence.
    • The longer the promoter, the more available space for proteins to bind.
    • They are not general transcription factors that bind to every promoter complex, but are recruited to a specific sequence on the promoter of a specific gene.
    • A generalized promoter of a gene transcribed by RNA polymerase II is shown.
    • Transcription factors recognize the promoter.

  • Initiation of Transcription in Prokaryotes

    • A promoter is a DNA sequence onto which the transcription machinery binds and initiates transcription .
    • In most cases, promoters exist upstream of the genes they regulate.
    • Although promoters vary among prokaryotic genomes, a few elements are conserved.
    • At the -10 and -35 regions upstream of the initiation site, there are two promoter consensus sequences, or regions that are similar across all promoters and across various bacterial species.
    • The σ subunit of prokaryotic RNA polymerase recognizes consensus sequences found in the promoter region upstream of the transcription start sight.

  • Catabolite Activator Protein (CAP): An Activator Regulator

    • When glucose levels decline in E. coli, catabolite activator protein (CAP) is bound by cAMP to promote transcription of the lac operon.
    • When glucose levels decline in the cell, accumulating cAMP binds to the positive regulator catabolite activator protein (CAP), a protein that binds to the promoters of operons that control the processing of alternative sugars, such as the lac operon.
    • When cAMP binds to CAP, the complex binds to the promoter region of the genes that are needed to use the alternate sugar sources .
    • In these operons, a CAP-binding site is located upstream of the RNA-polymerase-binding site in the promoter.
    • This increases the binding ability of RNA polymerase to the promoter region and the transcription of the genes.

  • Transcriptional Enhancers and Repressors

    • 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.
    • Therefore, a nucleotide sequence thousands of nucleotides away can fold over and interact with a specific promoter .
    • Transcriptional repressors can bind to promoter or enhancer regions and block transcription.
    • An enhancer is a DNA sequence that promotes transcription.

  • Auxins, Cytokinins, and Gibberellins

    • They also control the differentiation of meristem into vascular tissue and promote leaf development and arrangement.
    • IAA is used as a rooting hormone to promote growth of adventitious roots on cuttings and detached leaves.
    • Applying synthetic auxins to tomato plants in greenhouses promotes normal fruit development.
    • Outdoor application of auxin promotes synchronization of fruit setting and dropping, which coordinates the harvesting season.
    • The stimulating growth factor was found to be cytokinin, a hormone that promotes cytokinesis (cell division).

  • Initiation of Transcription in Eukaryotes

    • The completed assembly of transcription factors and RNA polymerase bind to the promoter, forming a transcription pre-initiation complex (PIC).
    • The most-extensively studied core promoter element in eukaryotes is a short DNA sequence known as a TATA box, found 25-30 base pairs upstream from the start site of transcription.
    • Only about 10-15% of mammalian genes contain TATA boxes, while the rest contain other core promoter elements, but the mechanisms by which transcription is initiated at promoters with TATA boxes is well characterized.
    • A generalized promoter of a gene transcribed by RNA polymerase II is shown.
    • Transcription factors recognize the promoter, RNA polymerase II then binds and forms the transcription initiation complex.

  • Abscisic Acid, Ethylene, and Nontraditional Hormones

    • Its activity counters many of the growth-promoting effects of GAs and auxins.
    • ABA induces dormancy in seeds by blocking germination and promoting the synthesis of storage proteins.
    • The best-known effect of the hormone, however, is the promotion of fruit ripening .
    • Strigolactones promote seed germination in some species and inhibit lateral apical development in the absence of auxins.
    • The plant hormone ethylene promotes ripening, as seen in the ripening of dates.

  • Cell Signaling and Cell Growth

    • The ligands that promote cell growth are called growth factors.

  • The trp Operon: A Repressor Operon

    • The promoter sequence is upstream of the transcriptional start site.
    • Each operon has a sequence within or near the promoter to which proteins (activators or repressors) can bind and regulate transcription.
    • A DNA sequence called the operator sequence is encoded between the promoter region and the first trp-coding gene.

  • 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.