title: Identification of 70 calcium-sensing receptor mutations in hyper- and hypo-calcaemic patients: evidence for clustering of extracellular domain mutations at calcium-binding sites.
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 (Ca(2+))-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 Ca(2+)-binding sites, particularly at the VFTD cleft, which is the principal site of Ca(2+) 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 Ca(2+) by the CaSR. Thus, these studies of disease-associated CaSR mutations have further elucidated the role of the VFTD cleft region in Ca(2+) binding and the function of the CaSR.
authors.affiliation: Academic Endocrine Unit, Nuffield Department of Clinical Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Oxford, UK.
authors.forename: Fadil M
authors.initials: FM
authors.lastname: Hannan
authors.forename: M Andrew
authors.initials: MA
authors.lastname: Nesbit
authors.forename: Chen
authors.initials: C
authors.lastname: Zhang
authors.forename: Treena
authors.initials: T
authors.lastname: Cranston
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Curley
authors.forename: Brian
authors.initials: B
authors.lastname: Harding
authors.forename: Carl
authors.initials: C
authors.lastname: Fratter
authors.forename: Nigel
authors.initials: N
authors.lastname: Rust
authors.forename: Paul T
authors.initials: PT
authors.lastname: Christie
authors.forename: Jeremy J O
authors.initials: JJ
authors.lastname: Turner
authors.forename: Manuel C
authors.initials: MC
authors.lastname: Lemos
authors.forename: Michael R
authors.initials: MR
authors.lastname: Bowl
authors.forename: Roger
authors.initials: R
authors.lastname: Bouillon
authors.forename: Caroline
authors.initials: C
authors.lastname: Brain
authors.forename: Nicola
authors.initials: N
authors.lastname: Bridges
authors.forename: Christine
authors.initials: C
authors.lastname: Burren
authors.forename: John M
authors.initials: JM
authors.lastname: Connell
authors.forename: Heike
authors.initials: H
authors.lastname: Jung
authors.forename: Eileen
authors.initials: E
authors.lastname: Marks
authors.forename: David
authors.initials: D
authors.lastname: McCredie
authors.forename: Zulf
authors.initials: Z
authors.lastname: Mughal
authors.forename: Christine
authors.initials: C
authors.lastname: Rodda
authors.forename: Sherida
authors.initials: S
authors.lastname: Tollefsen
authors.forename: Edward M
authors.initials: EM
authors.lastname: Brown
authors.forename: Jenny J
authors.initials: JJ
authors.lastname: Yang
authors.forename: Rajesh V
authors.initials: RV
authors.lastname: Thakker
mesh_terms: D001665:Binding Sites / Q000235:genetics; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D005838:Genotype; D057809:HEK293 Cells; D006801:Humans; D006934:Hypercalcemia / Q000235:genetics*; D006961:Hyperparathyroidism; D006996:Hypocalcemia / Q000235:genetics*; D007231:Infant, Newborn; D008958:Models, Molecular; D009154:Mutation; D059645:Mutation Rate; D020125:Mutation, Missense; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D044169:Receptors, Calcium-Sensing / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D044169:Receptors, Calcium-Sensing; D002118:Calcium