TRPP1 (polycystin-2, PC2, PKD2) belongs to the TRPP subfamily of TRP channels along with TRPP3 and TRPP5 proteins, and forms non-selective cation channels with different permeability to various divalent cations. The cellular localization of TRPP1 has been and still is the subject of a lasting debate. In many cell-types, TRPP1 is retained in the endoplasmic reticulum (ER) where it most likely functions as Ca2+ release channel, and with the help of cofactors, TRPP2 reaches the plasma membrane and the cilia8. TRPP1 expression is widespread and is best characterized for its expression in the kidney where it is developmentally regulated. In the kidney, it associates with PKD1 (TRPP2) an eleven transmembrane-spanning protein (which does not belong to the TRP superfamily) to form functional channels11. In addition, TRPP1 is identified as one of the genes responsible for autosomal dominant polycystic kidney disease (ADPKD).