Functional importance of the Ala(116)-Pro(136) region in the calcium-sensing receptor. Constitutive activity and inverse agonism in a family C G-protein-coupled receptor
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Functional importance of the Ala(116)-Pro(136) region in the calcium-sensing receptor. Constitutive activity and inverse agonism in a family C G-protein-coupled receptor. / Jensen, Anders A.; Spalding, T A; Burstein, E S; Sheppard, P O; O'Hara, P J; Brann, M R; Krogsgaard-Larsen, P; Bräuner-Osborne, H.
In: Journal of Biological Chemistry, Vol. 275, No. 38, 2000, p. 29547-55.Research output: Contribution to journal › Journal article › Research › peer-review
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T1 - Functional importance of the Ala(116)-Pro(136) region in the calcium-sensing receptor. Constitutive activity and inverse agonism in a family C G-protein-coupled receptor
AU - Jensen, Anders A.
AU - Spalding, T A
AU - Burstein, E S
AU - Sheppard, P O
AU - O'Hara, P J
AU - Brann, M R
AU - Krogsgaard-Larsen, P
AU - Bräuner-Osborne, H
PY - 2000
Y1 - 2000
N2 - The calcium-sensing receptor (CaR) belongs to family C of the G-protein-coupled receptor superfamily. To date 14 activating mutations in CaR showing increased sensitivity to Ca(2+) have been identified in humans with autosomal dominant hypocalcemia. Four of these activating mutations are found in the Ala(116)-Pro(136) region of CaR, indicating that this part of the receptor is particularly sensitive to mutation-induced activation. This region was subjected to random saturation mutagenesis, and 219 mutant receptor clones were isolated and screened pharmacologically in a high throughput screening assay. Selected mutants were characterized further in an inositol phosphate assay. The vast majority of the mutants tested displayed an increased affinity for Ca(2+). Furthermore, 21 of the mutants showed increased basal activity in the absence of agonist. This constitutive activity was not diminished when the mutations were transferred to a chimeric receptor Ca/1a consisting of the amino-terminal domain of the CaR and the 7 transmembrane and intracellular domains of the metabotropic glutamate receptor mGluR1a. CPCCOEt, a noncompetitive antagonist acting at the 7 transmembrane domain of mGluR1a, suppressed the elevated basal response of the constitutively activated Ca/1a mutants demonstrating inverse agonist activity of CPCCOEt. Taken together, our results demonstrate that the Ala(116)-Pro(136) region is of key importance for the maintenance of the inactive conformation of CaR.
AB - The calcium-sensing receptor (CaR) belongs to family C of the G-protein-coupled receptor superfamily. To date 14 activating mutations in CaR showing increased sensitivity to Ca(2+) have been identified in humans with autosomal dominant hypocalcemia. Four of these activating mutations are found in the Ala(116)-Pro(136) region of CaR, indicating that this part of the receptor is particularly sensitive to mutation-induced activation. This region was subjected to random saturation mutagenesis, and 219 mutant receptor clones were isolated and screened pharmacologically in a high throughput screening assay. Selected mutants were characterized further in an inositol phosphate assay. The vast majority of the mutants tested displayed an increased affinity for Ca(2+). Furthermore, 21 of the mutants showed increased basal activity in the absence of agonist. This constitutive activity was not diminished when the mutations were transferred to a chimeric receptor Ca/1a consisting of the amino-terminal domain of the CaR and the 7 transmembrane and intracellular domains of the metabotropic glutamate receptor mGluR1a. CPCCOEt, a noncompetitive antagonist acting at the 7 transmembrane domain of mGluR1a, suppressed the elevated basal response of the constitutively activated Ca/1a mutants demonstrating inverse agonist activity of CPCCOEt. Taken together, our results demonstrate that the Ala(116)-Pro(136) region is of key importance for the maintenance of the inactive conformation of CaR.
KW - 3T3 Cells
KW - Amino Acid Sequence
KW - Animals
KW - Base Sequence
KW - GTP-Binding Proteins
KW - Mice
KW - Molecular Sequence Data
KW - Mutagenesis
KW - Protein Conformation
KW - Receptors, Calcium-Sensing
KW - Receptors, Cell Surface
KW - Signal Transduction
KW - Structure-Activity Relationship
U2 - 10.1074/jbc.M910023199
DO - 10.1074/jbc.M910023199
M3 - Journal article
C2 - 10835431
VL - 275
SP - 29547
EP - 29555
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 38
ER -
ID: 38485384