The technical challenge in proving that a given expressed pseudogene is in fact translated into a functional protein is specificity. To circumvent this challenge, one approach is to use PCR in order to generate a series of clones that allow expression of the protein of interest either native or fused to a tag, which can facilitate purification, detection, and complementation in both bacterial and mammalian cells. This approach allows an assessment of whether a putative pseudogenic protein possesses enzymatic activity, to identify its subcellular localization and to test its capacity to complement the parental homologue.