Phenotypic Knockdown with Intrabodies

Intracellular antibodies (intrabodies) are antibody molecules which are expressed intracellularly and which are located in defined subcellular compartments, for example, the endoplasmic reticulum (ER). The amount of any surface protein (target protein) on a mammalian cell can be downregulated significantly by transfection with an expression vector encoding the intrabody that is specific for the target protein. To analyze the phenotypic knockdown of the target protein, either flow cytometry or fluorescence microscopy can be applied. In this article, we provide detailed protocols for both methods.