Operation
Gal4 is a modular protein consisting broadly of a DNA-binding domain and an activation domain. The UAS to which Gal4 binds is CGG-N11-CCG, where N can be any base. Although Gal4 is a yeast protein not normally present in other organisms it has been shown to work as a transcription activator in a variety of organisms such as Drosophila, and human cells, highlighting that the same mechanisms for gene expression have been conserved over the course of evolution.
For study in Drosophila, the GAL4 gene is placed under the control of a native gene promoter, or driver gene, while the UAS controls expression of a target gene. GAL4 is then only expressed in cells where the driver gene is usually active. In turn, Gal4 should only activate gene transcription where a UAS has been introduced. For example, by fusing a gene encoding a visible marker such as GFP (Green Fluorescent Protein) the expression pattern of the driver genes can be determined. GAL4 and the UAS are very useful for studying gene expression in Drosophila as they are not normally present and their expression does not interfere with other processes in the cell. For example, Gal4/UAS-regulated transgenes in Drosophila have been used to alter glial expression to produce arrhythmic behavior in a known rhythmic circadian output called pigment dispersing factor (pdf). However, some research has indicated that over-expression of GAL4 in Drosophila can have side-effects, probably relating to immune and stress responses to what is essentially an alien protein.
The GAL4-UAS system has also been employed to study gene expression in organisms besides Drosophila, such as the African clawed frog Xenopus and zebrafish.
The GAL4/UAS system is also utilized in Two-Hybrid Screening, a method of identifying interactions between two proteins or a protein with DNA.
Read more about this topic: GAL4/UAS System
Famous quotes containing the word operation:
“An absolute can only be given in an intuition, while all the rest has to do with analysis. We call intuition here the sympathy by which one is transported into the interior of an object in order to coincide with what there is unique and consequently inexpressible in it. Analysis, on the contrary, is the operation which reduces the object to elements already known.”
—Henri Bergson (1859–1941)
“Human knowledge and human power meet in one; for where the cause is not known the effect cannot be produced. Nature to be commanded must be obeyed; and that which in contemplation is as the cause is in operation as the rule.”
—Francis Bacon (1560–1626)
“It is critical vision alone which can mitigate the unimpeded operation of the automatic.”
—Marshall McLuhan (1911–1980)