In molecular biology, a reporter gene (often simply reporter) is a gene that researchers attach to another gene of interest in cell culture, animals or plants. Certain genes are chosen as reporters because the characteristics they confer on organisms expressing them are easily identified and measured, or because they are selectable markers. Reporter genes are generally used to determine whether the gene of interest has been taken up by or expressed in the cell or organism population. Molecular biology is the study of biology at a molecular level. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... Epithelial cells in culture, stained for keratin (red) and DNA (green) Cell culture is the term applied when cells are grown in a synthetic environment. ... A selectable marker is a gene introduced into a cell, especially a bacterium or to cells in culture, that confers a trait suitable for artificial selection. ...

Common reporter genes

To introduce a reporter gene into an organism, researchers place the reporter gene and the gene of interest in the same DNA construct to be inserted into the cell or organism. For bacteria or eukaryotic cells in culture, this is usually in the form of a circular DNA molecule called a plasmid. It is important to use a reporter gene that is not natively expressed in the cell or organism under study, since the expression of the reporter is being used as a marker for successful uptake of the gene of interest. A DNA construct is an artificially constructed segment of nucleic acid that is going to be transplanted into a target tissue or cell. ... Kingdoms Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista A eukaryote (IPA: ) is an organism with a complex cell or cells, in which the genetic material is organized into a membrane-bound nucleus or nuclei. ... Figure 1: Schematic drawing of a bacterium with plasmids enclosed. ...

Commonly used reporter genes that induce visually identifiable characteristics usually involve fluorescent proteins; examples include the gene that encodes jellyfish green fluorescent protein (GFP), which causes cells that express it to glow green under UV light, and the enzyme luciferase, which catalyzes a reaction with a luciferin to produce light. Another common reporter in bacteria is the lac Z gene, which encodes the protein beta-galactosidase. This enzyme causes bacteria expressing the gene to appear blue when grown on a medium that contains the substrate analog X-gal (an inducer molecule such as IPTG is also needed under the native promoter). An example of a selectable-marker reporter in bacteria is the chloramphenicol acetyltransferase (CAT) gene, which confers resistance to the antibiotic chloramphenicol. GFP ribbon diagram from PDB database The green fluorescent protein (GFP) is a protein from the jellyfish Aequorea victoria that fluoresces green when exposed to blue light. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hook from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ... Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than soft X-rays. ... Luciferase is a generic name for enzymes commonly used in nature for bioluminescence. ... Luciferin is a generic name for light-emitting pigments found in organisms capable of bioluminescence, like fireflies, deep-sea fish and microbes. ... Lactase (or β-galactosidase) is the enzyme involved in the hydrolysis of lactose to galactose and glucose. ... In gene cloning X-gal (5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside) is used to indicate whether a bacterium expresses the Beta-galactosidase enzyme, which is encoded by the lacZ gene. ... Common abbreviation for Isopropyl β-D-1-thiogalactopyranoside, a molecular biology reagent. ... Chloramphenicol acetyltransferase is a bacterial enzyme that detoxifies the antibiotic chloramphenicol. ... Chloramphenicol is a bacteriostatic antibiotic originally derived from the bacterium Streptomyces venezuelae, isolated by David Gottlieb, and introduced into clinical practice in 1949. ...

Transformation and transfection assays

Many methods of transfection and transformation - two ways of expressing a foreign or modified gene in an organism - are effective in only a small percentage of a population subjected to the techniques. Thus, a method for identifying those few successful gene uptake events is necessary. Reporter genes used in this way are normally expressed under their own promoter independent from that of the introduced gene of interest; the reporter gene can be expressed constitutively (that is, it is "always on") or inducibly with an external intervention such as the introduction of IPTG in the beta-galactosidase system. As a result, the reporter gene's expression is independent of the gene of interest's expression, which is an advantage when the gene of interest is only expressed under certain specific conditions or in tissues that are difficult to access. Introducing DNA into eukaryotic cells, such as animal cells, is called transfection. ... Transformation is the genetic alteration of a cell resulting from the introduction, uptake and expression of foreign genetic material (DNA or RNA). ... In genetics, a promoter is a DNA sequence that enables a gene to be transcribed. ...

In the case of selectable-marker reporters such as CAT, the transfected population of bacteria can be grown on a substrate that contains chloramphenicol. Only those cells that have successfully taken up the construct containing the CAT gene will survive and multiply under these conditions.

Gene expression assays

Reporter genes can also be used to assay for the expression of the gene of interest, which may produce a protein that has little obvious or immediate effect on the cell culture or organism. In these cases the reporter is directly attached to the gene of interest to create a gene fusion. The two genes are under the same promoter and are transcribed into a single polypeptide chain. In these cases it is important that both proteins be able to properly fold into their active conformations and interact with their substrates despite being fused. In building the DNA construct, a segment of DNA coding for a flexible polypeptide linker region is usually included so that the reporter and the gene product of will only minimally interfere with one another. Gene-Fusion is a 26 part animated television series produced by Banjax based on an original comic from Beckett Entertainment. ... Transcription is the process through which a DNA sequence is enzymatically copied by an RNA polymerase to produce a complementary RNA. Or, in other words, the transfer of genetic information from DNA into RNA. In the case of protein-encoding DNA, transcription is the beginning of the process that ultimately... Peptides (from the Greek πεπτος, digestible), are the family of short molecules formed from the linking, in a defined order, of various α-amino acids. ... Protein folding is the process by which a protein assumes its characteristic functional shape or tertiary structure, also known as the native state. ...

Promoter assays

Reporter genes can be used to assay for the activity of a particular promoter in a cell or organism. In this case there is no separate "gene of interest"; the reporter gene is simply placed under the control of the target promoter and the reporter gene product's activity is quantitatively measured. The results are normally reported relative to the activity under a "consensus" promoter known to induce strong gene expression.

Further uses

A more complex usage of reporter genes on a large scale is in two-hybrid screening, which aims to identify proteins that natively interact with one another in vivo. Overview of two-hybrid assay as follows. ... In vivo (Latin for (with)in the living). ...

See also

• GUS reporter system