- 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, A.A., Spalding, T.A., Burstein, E.S., Sheppard, P.O., O'Hara, P.J., Brann, M.R., Krogsgaard-Larsen, P., Bräuner-Osborne, H. J. Biol. Chem. (2000)