When negative is positive in functional genomics.

The post-genomic era has caused classical approaches to analyse gene function to be reviewed and refined. Conventional reverse genetic approaches to predict gene function have drawbacks in terms of genetic redundancy and being limited mainly to well-characterized genomes. The relatively recent use of dominant-negative transgenes has been successful in elaborating certain pathways and it is now possible to extend this technique to convert transcription factors into dominant repressor functions by fusion to repressor domains such as ENGRAILED from Drosophila. This methodology opens up new possibilities to overcome genetic redundancy, to identify novel gene functions and also to apply information on conserved protein domains between species to repress heterologous protein function.