The long-term goal of this research project is to understand the mechanisms underlying Ca2+-mediated signaling and the molecular basis for diseases associated with alterations in Ca2+ homeostasis. Extracellular Ca2+ ([Ca2+]o) has been proposed to function as a first messenger to trigger diverse cellular processes. Ca2+-sensing receptors (CaRs) represent a class of receptors that respond to changes in [Ca2+]o and activate multiple signaling pathways. By serving as the body's """"""""thermostats"""""""" for [Ca2+]o, CaRs play a central role in the regulation of [Ca2+]o homeostasis and represent important therapeutic targets. A major barrier to advancing our understanding of the role of Ca2+ in regulating CaRs is the lack of adequate information about the location of their Ca2+-binding sites and the structural information of this class of membrane proteins. Obtaining site-specific Ca2+-binding affinities of naturally-occurring proteins is hampered by the complexities encountered in cooperative, multi-site systems. The delineation of the Ca2+-binding sites in the CaR and related proteins is further hindered by limitations of crystallization conditions, rapid off-rates owing to low Ca2+-binding affinities and the existence of multiple conformations that are in equilibrium with one another.The immediate goals of this proposal are to 1) probe Ca2+-binding sites in the Ca2+-sensing receptors and 2) verify our prediction of specific Ca2+-binding sites by correlating the site-specific and domain-specific Ca2+-binding information with the biological activity of the w.t. receptor in mammalian cells as well as receptors with mutations in these Ca2+-binding sites. Results from our proposed work will have a major impact on the understanding of the mechanisms underlying the biological activities carried out by Ca2+-modulated receptors. These proposed investigations will provide novel methods for identifying Ca2+- binding sites in the CaR and related proteins, thus overcoming the major obstacles encountered in visualizing Ca2+-binding sites with weak binding affinities. Success in identifying Ca2+-binding sites and clarifying how Ca2+ regulates the CaR will not only promote an understanding of how Ca2+ functions as an extracellular messenger, but will also provide insights into the molecular basis of the clinical disorders associated with this receptor. Our success in designing and engineering metal-binding sites into arbitrary proteins could also lead to new ways of developing valuable reagents for diagnostic tests and chemotherapy.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM081749-03
Application #
7684655
Study Section
Biochemistry and Biophysics of Membranes Study Section (BBM)
Program Officer
Basavappa, Ravi
Project Start
2007-09-01
Project End
2011-08-31
Budget Start
2009-09-01
Budget End
2010-08-31
Support Year
3
Fiscal Year
2009
Total Cost
$290,556
Indirect Cost
Name
Georgia State University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
837322494
City
Atlanta
State
GA
Country
United States
Zip Code
30302
Zou, Juan; Salarian, Mani; Chen, Yanyi et al. (2017) Direct visualization of interaction between calmodulin and connexin45. Biochem J 474:4035-4051
Gorkhali, Rakshya; Huang, Kenneth; Kirberger, Michael et al. (2016) Defining potential roles of Pb(2+) in neurotoxicity from a calciomics approach. Metallomics 8:563-78
Zhang, Chen; Zhang, Tuo; Zou, Juan et al. (2016) Structural basis for regulation of human calcium-sensing receptor by magnesium ions and an unexpected tryptophan derivative co-agonist. Sci Adv 2:e1600241
Tang, Shen; Reddish, Florence; Zhuo, You et al. (2015) Fast kinetics of calcium signaling and sensor design. Curr Opin Chem Biol 27:90-7
Zhuo, You; Solntsev, Kyril M; Reddish, Florence et al. (2015) Effect of Ca²? on the steady-state and time-resolved emission properties of the genetically encoded fluorescent sensor CatchER. J Phys Chem B 119:2103-11
Zhang, Chen; Miller, Cassandra Lynn; Brown, Edward M et al. (2015) The calcium sensing receptor: from calcium sensing to signaling. Sci China Life Sci 58:14-27
Hsieh, Ying-Hsin; Zou, Juan; Jin, Jin-Shan et al. (2015) Monitoring channel activities of proteoliposomes with SecA and Cx26 gap junction in single oocytes. Anal Biochem 480:58-66
Feng, Jie; Xu, Xiaojun; Li, Bo et al. (2014) Prostate cancer metastatic to bone has higher expression of the calcium-sensing receptor (CaSR) than primary prostate cancer. Receptors Clin Investig 1:
Zhang, Chen; Mulpuri, Nagaraju; Hannan, Fadil M et al. (2014) Role of Ca2+ and L-Phe in regulating functional cooperativity of disease-associated ""toggle"" calcium-sensing receptor mutations. PLoS One 9:e113622
Zhang, Chen; Zhuo, You; Moniz, Heather A et al. (2014) Direct determination of multiple ligand interactions with the extracellular domain of the calcium-sensing receptor. J Biol Chem 289:33529-42

Showing the most recent 10 out of 37 publications