Protein i: interference at protein level by intrabodies.

Immunoglobulin molecules have long been used in biomedical research as in vitro tools for identification, purification and functional manipulation of target proteins. The specificity and diversity of immunoglobulins can be exploited to target a wide range of intracellular proteins by expressing them in vivo. Such antibody molecules, which are expressed intracellularly and directed to defined sub-cellular compartments, are termed 'intrabodies'. They represent a new and versatile tool that has the potential to manipulate diverse biological processes. Gene knockout, antisense and small interfering RNA knockdown techniques, are employed to characterize the function of many gene products and to validate these gene products as potential drug targets for novel therapeutics, but they have their limitations. The experimental results to date suggest that intrabodies represent a powerful alternative to modulate protein function and analyze its effects. Moreover, they can also be utilized to target specific domains of a particular target protein. Even though their clinical application might take a long time, they can play an important role for target identification and validation in functional genomics and/or proteomics. Here we review the latest advances in the concept, construction and applications of Intrabodies.