The prion-like protein doppel (Dpl) interacts with the human receptor for activated C-kinase 1 (RACK1) protein

Background: Doppel (Dpl) is a homologue of the prion protein (PrPC). In contrast to PrPC, Dpl is dispensable for prion disease, but appears to have an essential function in male spermatogenesis. Recently, Dpl has been found to be aberrantly expressed in astrocytic and leukaemic tumor specimens, showing a peculiar cytosolic cellular localization. The aim of this study was to clarify some of the putative Dpl interacting proteins. Materials and Methods: A yeast two hybrid system was employed and the results were verified by co-immunoprecipitation using transfected cells. Results: Several potential Dpl-binding candidates were identified and, among them, the receptor for activated C-kinase (RACK1) protein was further investigated. RACK1 deletion mutants showed that some of its WD containing domains were directly involved in the binding with Dpl. Our data showed that Dpl interacts with RACK1 by means of its structured globular carboxyl-terminal region. Conclusion: This new Dpl interacting partner might suggest functional hypotheses about the role of this protein in an astrocytoma context where Dpl was found ectopically expressed.