Identification of 70 calcium-sensing receptor mutations in hyper- and hypo-calcaemic patients: evidence for clustering of extracellular domain mutations at calcium-binding sites
Open Access
- 14 March 2012
- journal article
- research article
- Published by Oxford University Press (OUP) in Human Molecular Genetics
- Vol. 21 (12), 2768-2778
- https://doi.org/10.1093/hmg/dds105
Abstract
The calcium-sensing receptor (CaSR) is a G-protein-coupled receptor that has an extracellular bilobed venus flytrap domain (VFTD) predicted to contain five calcium (Ca2+)-binding sites. To elucidate the structure–function relationships of the VFTD, we investigated 294 unrelated probands with familial hypocalciuric hypercalcaemia (FHH), neonatal severe primary hyperparathyroidism (NSHPT) or autosomal dominant hypocalcaemic hypercalciuria (ADHH) for CaSR mutations and performed in vitro functional expression studies and three-dimensional modelling of mutations involving the VFTD. A total of 70 different CaSR mutations were identified: 35 in FHH, 10 in NSHPT and 25 in ADHH patients. Furthermore, a CaSR variant (Glu250Lys) was identified in FHH and ADHH probands and demonstrated to represent a functionally neutral polymorphism. NSHPT was associated with a large proportion of truncating CaSR mutations that occurred in the homozygous or compound heterozygous state. Thirty-four VFTD missense mutations were identified, and 18 mutations were located within 10 Å of one or more of the predicted Ca2+-binding sites, particularly at the VFTD cleft, which is the principal site of Ca2+ binding. Mutations of residues 173 and 221, which are located at the entrance to the VFTD cleft binding site, were associated with both receptor activation (Leu173Phe and Pro221Leu) and inactivation (Leu173Pro and Pro221Gln), thereby highlighting the importance of these residues for entry and binding of Ca2+ by the CaSR. Thus, these studies of disease-associated CaSR mutations have further elucidated the role of the VFTD cleft region in Ca2+ binding and the function of the CaSR.Keywords
This publication has 30 references indexed in Scilit:
- Multiple Ca2+-Binding Sites in the Extracellular Domain of the Ca2+-Sensing Receptor Corresponding to Cooperative Ca2+ ResponseBiochemistry, 2008
- Identification and Dissection of Ca2+-binding Sites in the Extracellular Domain of Ca2+-sensing ReceptorJournal of Biological Chemistry, 2007
- Elucidation of the Role of Peptide Linker in Calcium-sensing Receptor Activation ProcessPublished by Elsevier BV ,2007
- Impaired cotranslational processing of the calcium-sensing receptor due to signal peptide missense mutations in familial hypocalciuric hypercalcemiaHuman Molecular Genetics, 2005
- The Venus Fly Trap Domain of the Extracellular Ca2+-sensing Receptor Is Required for l-Amino Acid SensingJournal of Biological Chemistry, 2004
- Modulation of Interprotomer Relationships Is Important for Activation of Dimeric Calcium-sensing ReceptorJournal of Biological Chemistry, 2004
- Diseases associated with the extracellular calcium-sensing receptorCell Calcium, 2004
- Extracellular calcium sensing and signallingNature Reviews Molecular Cell Biology, 2003
- The Agonist-binding Domain of the Calcium-sensing Receptor Is Located at the Amino-terminal DomainJournal of Biological Chemistry, 1999
- Cloning and characterization of an extracellular Ca2+-sensing receptor from bovine parathyroidNature, 1993