The Britten-Davidson model is a widely accepted and influential model of gene regulation that was developed by David Britten and Roy J. Davidson in the 1970s. It is a mathematical model that describes the regulation of gene expression, which is the process by which genes are turned on or off in cells.
One key aspect of the Britten-Davidson model is its focus on the role of transcription factors, which are proteins that bind to specific DNA sequences and regulate the transcription of genes into RNA. In the model, transcription factors are depicted as "activators" or "repressors," depending on whether they stimulate or inhibit gene expression.
Another key concept in the model is the "operon," which refers to a group of genes that are regulated together and are transcribed into a single mRNA molecule. Operons can be regulated at the level of transcription, where transcription factors bind to specific DNA sequences and regulate the initiation of transcription, or at the level of translation, where proteins or other molecules bind to the mRNA and inhibit its translation into protein.
The Britten-Davidson model also describes how gene expression can be regulated in a hierarchical manner, with transcription factors regulating the expression of other transcription factors and ultimately controlling the expression of specific genes. This hierarchical regulation allows for complex patterns of gene expression, with multiple layers of control and feedback loops that can fine-tune gene expression in response to different cellular signals and conditions.
Overall, the Britten-Davidson model has had a significant impact on our understanding of gene regulation and has helped to pave the way for further research in this area. It remains an important and widely cited model in the field of molecular biology, and continues to be a useful tool for researchers studying gene regulation and its role in the development and function of cells and organisms.
Britten & Davidson Model
Post-Transcriptional Regulation of Gene Expression in Eukaryotes : Post-transcriptional regulation of gene expression may occur in different ways. This model was suggested as a working hypothesis in the 1960s for interpreting the processes involved in the regulation of eukaryotic gene functions. Enhancer: ADVERTISEMENTS: The transcriptional factors are produced constitutively, but except these there are some transcriptional activators TAs which bind to the enhancer site situated many hundreds base pairs from the promoter site. The external stimuli were supposed to be directed to sensor genes that activated integrator genes that in turn transmitted the signals to receptor genes, which affected than the structural genes, coding for protein. These transcriptional activators are induced proteins, i. Gene regulation helps a unicellular organism to adapt well to the environment.
R. J. Britten & E. H. Davidson, Gene regulation for higher cells : a theory
ADVERTISEMENTS: GC Box: Another element often seen in some promoter regions, called the GC box, has the consensus sequence GGGCGG and is found at about position -110, often occurs in multiple copies, the GC elements bind transcription factors and function more like enhancer. Britten RJ, Davidson EH 1969 Science 165:349; Britten RJ 1998 Proc Natl Acad Sci USA 95:9372. The receptor dimerizes and is trans-located to the nucleus where it binds to target gene promoters activating transcription. Reversible phosphorylation machinery is involved in the regulation of gene expression, as the phosphorylated or dephosphorylated forms of the components of translational machinery should identify a specific mRNA from the bulk mRNA population. This model assumes the presence of four classes of sequences Fig. A complex consisting of all transcriptional factors determine which RNA polymerase binds and which gene can be transcribed, and the complex is called pre-initiation complex.
Regulation of Gene Expression in Eukaryotes
Steroid hormones on entering cells, bind steroid hormone receptor protein, releasing it from an inhibitory protein. Transactivation domains have no motifs but are often enriched with acidic amino acid, glutamines or pro-lines. In this model the genes producer gene and integrator gene are involved in RNA synthesis whereas receptor and sensor sites are those sequences which help only in recognition without taking part in RNA synthesis. The message is then complexed with proteins and exported to the cytoplasm. The transcription factors have a modular structure containing DNA binding, dimerization and transactivation domains. Cite this entry 2008.
The establishment of this concept 1 has depended on evidence indicating that the cells of an organism generally contain identical genomes 2. Each producer gene may have several receptor sites, each responding to one activator Fig. Gene Battery: ADVERTISEMENTS: Among the various models, the Britten and Davidson model for regulation of protein synthesis in eukaryotes is most popular. ADVERTISEMENTS: Promoter: This is a site for regulation of transcription. Expand Chromatin isolated by the methods now available, together with the basis provided by the present knowledge of chromatin biochemistry and biophysics, should make possible and indeed assure rapid increase in knowledge of chromosomal structure and of all aspects of the control of gene activity and hence of developmental processes.
