Analysis of the cytoplasmic interaction between polycystin-1 and polycystin-2

Departments of 1 Pharmacology and ; 4 Cellular and Molecular Physiology and ; 3 W. M. Keck Foundation Biotechnology Resource Laboratory, Yale University School of Medicine, New Haven, Connecticut Submitted July 22, 2009 ; accepted in final form September 2, 2009 Autosomal dominant polycystic kidney disease (ADPKD) arises following mutations of either Pkd1 or Pkd2 . The proteins these genes encode, polycystin-1 (PC1) and polycystin-2 (PC2), form a signaling complex using direct intermolecular interactions. Two distinct domains in the C-terminal tail of PC2 have recently been identified, an EF-hand and a coiled-coil domain. Here, we show that the PC2 coiled-coil domain interacts with the C-terminal tail of PC1, but that the PC2 EF-hand domain does not. We measured the K 0.5 of the interaction between the C-terminal tails of PC1 and PC2 and showed that the direct interaction of these proteins is abrogated by a PC1 point mutation that was identified in ADPKD patients. Finally, we showed that overexpression of the PC1 C-terminal tail in MDCK cells alters the Ca 2+ response, but that overexpression of the PC1 C-terminal tail containing the disease mutation does not. These results allow a more detailed understanding of the mechanism of pathogenic mutations in the cytoplasmic regions of PC1 and PC2. polycystic kidney disease; calcium signaling; surface plasmon resonance; EF-hand; coiled-coil domain Address for reprint requests and other correspondence: T. J. Boggon and B. E. Ehrlich, Dept. of Pharmacology, Yale Univ. School of Medicine, 333 Cedar Str., New Haven, CT 06520-8066 (e-mail: titus.boggon{at}yale.edu ).