14-3-3 proteins in calcium-sensing receptor signalling
The Calcium-sensing receptor (CaR) belongs to Family C of G protein-coupled receptors. The receptor’s main role is to maintain calcium homeostasis. In addition, the CaR plays an important functional role in processes such as cell proliferation and apoptosis. These processes are mediated by various intracellular signalling pathways and the CaR tail is believed to play a major role in receptor signal transduction. To provide insight into mechanisms that control CaR signalling, recent yeast two-hybrid (Y2H) studies in our laboratory, using the CaR tail as bait, identified a number of interacting proteins including two isoforms of 14-3-3 (theta and zeta). 14-3-3 proteins are ubiquitously expressed and highly conserved, and are emerging as a group of multifunctional adapter proteins with a recognised role as chaperones. 14-3-3 proteins bind to numerous partner proteins and have a preference for targets containing phosphorylated motifs. Y2H deletion mapping studies performed in our laboratory have delineated the interaction region for 14-3-3 theta to residues 865-923 in the CaR tail. This region contains a consensus 14-3-3 binding motif that includes serine 895, a known protein kinase C substrate. The in vivo interaction between the CaR and 14-3-3 theta has been demonstrated by co-immunoprecipitation in mammalian cells. In addition, a direct in vitro interaction has been confirmed between 14-3-3 theta and the CaR tail using pulldown assays. An immediate aim of our studies is to establish the significance of the consensus 14-3-3 interaction motif in CaR signalling.
Arulpragasam, A., Ward, B. K., Magno, A. L., Ingley, E., & Ratajczak, T. (2007). Paper presented at the Australian Society for Medical Research Western Australia Scientific Symposium, 2007.