7SIM

Structure of positive allosteric modulator-free active human calcium-sensing receptor

Summary for 7SIM

• Entry DOI: 10.2210/pdb7sim/pdb
• EMDB information: 25144
• Descriptor: Isoform 1 of Extracellular calcium-sensing receptor, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, 2-acetamido-2-deoxy-beta-D-glucopyranose, ... (7 entities in total)
• Functional Keywords: calcium-sensing receptor, cryo-em structure, allosteric modulation, activation mechanism, symmetry, membrane protein
• Biological source: Homo sapiens (Human)
• Total number of polymer chains: 2
• Total formula weight: 204775.21

Authors

Park, J.,Zuo, H.,Frangaj, A.,Fu, Z.,Yen, L.Y.,Zhang, Z.,Mosyak, L.,Slavkovich, V.N.,Liu, J.,Ray, K.M.,Cao, B.,Vallese, F.,Geng, Y.,Chen, S.,Grassucci, R.,Dandey, V.P.,Tan, Y.Z.,Eng, E.,Lee, Y.,Kloss, B.,Liu, Z.,Hendrickson, W.A.,Potter, C.S.,Carragher, B.,Graziano, J.,Conigrave, A.D.,Frank, J.,Clarke, O.B.,Fan, Q.R. (deposition date: 2021-10-14, release date: 2022-01-19, Last modification date: 2024-11-06)

Primary citation

Park, J.,Zuo, H.,Frangaj, A.,Fu, Z.,Yen, L.Y.,Zhang, Z.,Mosyak, L.,Slavkovich, V.N.,Liu, J.,Ray, K.M.,Cao, B.,Vallese, F.,Geng, Y.,Chen, S.,Grassucci, R.,Dandey, V.P.,Tan, Y.Z.,Eng, E.,Lee, Y.,Kloss, B.,Liu, Z.,Hendrickson, W.A.,Potter, C.S.,Carragher, B.,Graziano, J.,Conigrave, A.D.,Frank, J.,Clarke, O.B.,Fan, Q.R.
Symmetric activation and modulation of the human calcium-sensing receptor.
Proc.Natl.Acad.Sci.USA, 118:-, 2021

PubMed Abstract: The human extracellular calcium-sensing (CaS) receptor controls plasma Ca levels and contributes to nutrient-dependent maintenance and metabolism of diverse organs. Allosteric modulation of the CaS receptor corrects disorders of calcium homeostasis. Here, we report the cryogenic-electron microscopy reconstructions of a near-full-length CaS receptor in the absence and presence of allosteric modulators. Activation of the homodimeric CaS receptor requires a break in the transmembrane 6 (TM6) helix of each subunit, which facilitates the formation of a TM6-mediated homodimer interface and expansion of homodimer interactions. This transformation in TM6 occurs without a positive allosteric modulator. Two modulators with opposite functional roles bind to overlapping sites within the transmembrane domain through common interactions, acting to stabilize distinct rotamer conformations of key residues on the TM6 helix. The positive modulator reinforces TM6 distortion and maximizes subunit contact to enhance receptor activity, while the negative modulator strengthens an intact TM6 to dampen receptor function. In both active and inactive states, the receptor displays symmetrical transmembrane conformations that are consistent with its homodimeric assembly.

PubMed: 34916296
DOI: 10.1073/pnas.2115849118

Experimental method

ELECTRON MICROSCOPY (2.7 Å)