Ubiquitin and proteasomes are involved in the degradation of cytosolic doppel protein

When HEK293 cells were transfected with a plasmid containing CMV promoter driven human wild-type PRND gene, the doppel protein was diffusely observed at the cytoplasm as seen in cancer cells. The transfected cells incubated with proteasome inhibitor N-acetyl-leucinal- leucinal- norleucinal (ALLN), resulted in apparent accumulation of the doppel protein. Furthermore, an alpha helix domain of the doppel protein appeared to be coimmunoprecipitated with ubiquitin related HSP70 protein. These findings suggested that the cytosolic doppel protein chaperoned with HSP70 could be subjected to ubiquitin proteasome degradation system.