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Regulation of gene expression by a hormone receptor Diagram showing at which stages in the DNA-mRNA-protein pathway expression can be controlled. Regulation of gene expression, or gene regulation, [1] includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products (protein or RNA).
Positive control elements that bind to DNA and incite higher levels of transcription. [3] While these means of transcriptional regulation also exist in eukaryotes, the transcriptional landscape is significantly more complicated both by the number of proteins involved as well as by the presence of introns and the packaging of DNA into histones.
The regulation of gene expression in eukaryotes is achieved through the interaction of several levels of control that acts both locally to turn on or off individual genes in response to a specific cellular need and globally to maintain a chromatin-wide gene expression pattern that shapes cell identity.
In DNA, regulation of gene expression normally happens at the level of RNA biosynthesis (transcription). It is accomplished through the sequence-specific binding of proteins (transcription factors) that activate or inhibit transcription. Transcription factors may act as activators, repressors, or both.
The stability of the final gene product, whether it is RNA or protein, also contributes to the expression level of the gene—an unstable product results in a low expression level. In general gene expression is regulated through changes [ 44 ] in the number and type of interactions between molecules [ 45 ] that collectively influence ...
Eukaryotes have a much larger genome and thus have different methods of gene regulation than in prokaryotes. All cells in a eukaryotic organism have the same DNA but are specified through differential gene expression, a phenomenon known as genetic totipotency. [7]
[1] [2] [5] Human transcripts possess 3′-UTRs that are on average twice as long as other mammalian 3′-UTRs. This trend reflects the high level of complexity involved in human gene regulation. In addition to length, the secondary structure of the 3′-untranslated region also has regulatory functions.
In eukaryotes, genes tend to be transcribed individually, and each gene is controlled by its own regulatory sequences. [2] Regulatory sequences where activators bind are commonly found upstream from the promoter, but they can also be found downstream or even within introns in eukaryotes. [1] [2] [3]