Editing Expression vector (section)

{{Short description|Virus or plasmid designed for gene expression in cells}}
[[File:PET28a-T7-lacO-GFP.svg|thumb|A bacterial expression vector for expressing [[green fluorescent protein]] from the [[T7 RNA polymerase|T7 promoter]].]]

An '''expression vector''', otherwise known as an '''expression construct''', is usually a [[plasmid]] or virus designed for [[gene expression]] in cells. The [[vector (molecular biology)|vector]] is used to introduce a specific [[gene]] into a target cell, and can commandeer the cell's mechanism for [[protein synthesis]] to produce the [[protein]] [[Genetic code|encoded]] by the gene.  Expression vectors are the basic tools in [[biotechnology]] for the [[protein production|production of proteins]].

The [[Vector (molecular biology)|vector]] is engineered to contain regulatory sequences that act as [[Enhancer (genetics)|enhancer]] and [[Promoter (biology)|promoter]] regions and lead to efficient transcription of the gene carried on the expression vector.<ref>[http://www.sci.sdsu.edu/~smaloy/MicrobialGenetics/topics/in-vitro-genetics/expression-vectors.html sci.sdsu.edu]</ref> The goal of a well-designed expression vector is the efficient production of protein, and this may be achieved by the production of significant amount of stable [[messenger RNA]], which can then be [[Translation (biology)|translated]] into protein. The expression of a protein may be tightly controlled, and the protein is only produced in significant quantity when necessary through the use of an [[inducer]].  In some systems, however, the protein may be expressed constitutively. ''[[Escherichia coli]]'' is commonly used as the host for [[protein production]], but other cell types may also be used. An example of the use of expression vector is the production of [[insulin]], which is used for medical treatments of [[diabetes]].