noun, plural: expression vectors
The expression vector is a plasmid engineered to introduce a particular gene into the target cell. The plasmid contains the regulatory sequences that serve as enhancer and promoter regions needed for the expression of a specific gene using the transcription and translation machinery of the target cell.
An example of expression vector is the plasmid used to produce insulin important for treating diseases such as diabetes. Another example is the expression vector that introduces specific genes necessary for the synthesis of beta-carotene into the cells of rice plants, giving rise to a new variety called golden rice.