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              Printable Handouts
Navigable Slide Index
- Introduction
 - Class C G-Protein Coupled Receptors
 - Questions
 - Human GABAB receptor
 - GABAB receptor
 - GABABR functions as an obligatory heterodimer
 - GBR1:GBR2 ecodomain heterodimer structures
 - Apo structure
 - Antagonist-bound structures
 - Agonist-bound structures
 - Heterodimer interactions: resting & active states
 - Agonist-binding induced conformational changes
 - Ligand binding site
 - Chemical structures of agonists and antagonists
 - Antagonist-binding site: GBR1:GBR2 complex
 - Contacts between GBR1 & different antagonists
 - Contacts between GBR1 & different agonists
 - Ligand-binding site of the GBR1:GBR2 complex
 - Agonist vs. Antagonist binding (1)
 - Agonist vs. Antagonist binding (2)
 - LB1 mutations in the ligand-binding site
 - LB2 mutations in the ligand-binding site
 - Implications for receptor activation
 - GBR2 closure not needed for receptor activation
 - Disulfide-lined GABABR heterodimer: Design
 - Disulfide-lined GABABR heterodimer: Formation
 - Interfacrial disulfide locks GABABR in active state
 - Conformational equilibrium of GABAB receptor
 - Human calcium-sensing receptor
 - Extracellular calcium-sensing receptor
 - Diverse function of calcium-sensing receptor
 - Crystallization of deglycosylated CaSR
 - CaSR extracellular domain: Inactive structure
 - CaSR extracellular domain: Active structure
 - Homodimer Interactions: Inactive & Active States
 - L-amino acid recognition
 - L-amino acids are orthosteric agonists of CaSR
 - Common agonist-binding mode: Class C GPCRs
 - CaSR-mediated intracellular Ca2+ mobilization
 - Amino acids increase CaSR sensitivity to Ca2+
 - L-amino acid binding is required for CaSR activity
 - Ca2+ -binding sites
 - Identification of Ca2+-binding sites in CaSR
 - Ca2+ maintains the structural integrity of CaSR
 - Ca2+ stabilizes the active conformation of CaSR
 - L-amino Acids and Ca2+ are co-agonists of CaSR
 - Endogenous agonist of CaSR
 - Anion binding sites
 - Identification of anion-binding sites in CaSR
 - PO43- maintains the structural integrity of CaSR
 - PO43- negative modulatory effect: CaSR activity
 - Agonist-binding induced conformation changes
 - Activation of CaSR: An intricate interplay
 - Activation mechanism of class C GPCRs
 - Common activation mechanism of class C GPCRs
 - Acknowledgements
 
Topics Covered
- Crystal structures of human GABA(B) receptor extracellular domain in multiple functional states
 - Agonist vs. antagonist recognition
 - Identification of novel heterodimer interface associated with receptor activation
 - Crystal structures of human CaSR in the inactive and active conformations
 - Discovery of L-amino acids as orthosteric agonists of CaSR
 - Identification of Ca2+ and PO43 binding sites in CaSR
 - Universal activation mechanism of class C GPCRs
 
Links
Series:
Categories:
Talk Citation
Fan, Q.R. (2019, July 31). Extracellular domain structures from calcium-sensing and GABA(B) receptors [Video file]. In The Biomedical & Life Sciences Collection, Henry Stewart Talks. Retrieved November 4, 2025, from https://doi.org/10.69645/RERY7138.Export Citation (RIS)
Publication History
- Published on July 31, 2019
 
Financial Disclosures
- Dr. Qing R. Fan has not informed HSTalks of any commercial/financial relationship that it is appropriate to disclose.
 
Other Talks in the Series: G Protein-Coupled Receptors (GPCRs) Signaling in Health and Disease
Transcript
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                  0:00
                
                
                  
                    My name is Qing Fan.
                  
                    I'm from Colombia University.
                  
                    The research in my lab involves
                  
                    the structural studies of class C G-protein coupled receptors.
                  
                
              
                  0:12
                
                
                  
                    GPCRs are divided into different classes
                  
                    based on the sequence homology of their trans-membrane domains.
                  
                    Most GPCRs such as rhodopsin and Beta-2 adrenergic receptor belong to class A.
                  
                    These receptors contain a seven helix trans-membrane domain and can function as monomers.
                  
                    The ligand binding site of
                  
                    the class A receptors is located within the trans-membrane domain.
                  
                    Landmark studies led by Dr. Kodaka's group revealed that agonist binding directly
                  
                    induces conformational changes among the trans-membrane helices for receptor activation.
                  
                    Class C GPCRs mediate a number of
                  
                    key biological phenomena including excitatory and inhibitory neurotransmission,
                  
                    calcium homeostasis, and taste.
                  
                    Unlike the class A receptors,
                  
                    the class GPCRs are characterized by a large extracellular domain.
                  
                    In addition to the canonical seven helix trans-membrane domain,
                  
                    this extracellular domain is 500-600 amino
                  
                    acids long and contains the orthosteric ligand binding site.
                  
                    Another unique feature of
                  
                    the class C receptors is that they require dimerization for function.
                  
                    While metabotropic glutamate receptors and calcium sensing
                  
                    receptor function as disulfide-linked homodimers,
                  
                    GABA B receptor and taste receptors are obligatory heterodimers.
                  
                    Our goal is to use structural methods to probe
                  
                    the signal transduction mechanisms of class C receptors and GPCR dimers in general.
                  
                    Specifically, we're focusing on human GABA B receptor and human calcium sensing receptor.
                  
                
              
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