Receptors chinRProten-Coupled Receptor Systems 5HTa serotonin R Cell Surface Multisubunit Ligand-gated lon channels GTP GDP Catalytic Activities: G Proteins: Effectors atawth factor tecentors Defined by Regulated by Cytoplasm a Subunits composition TGFB-rec I adenytyl cycase.Ca.cuments Nat exchange Nucleus regulated by 所subunits: phospholipase CB Figure 2-1.Structural motifs of physiologi and their relationships to signaling pathways. Classification of receptors(by structure and mode of action) 1)lon channel receptors:Include ligand-gated ion channels and voltage-gated ion channels 2)G protein-coupled receptors:Largest cell surface receptor family (or "superfamily").Also termed 7-TM (transmembrane domain)receptors 3)Kinase-linked receptors:These receptors have an extracellular ligand-binding domain and an intracellular kinase domain 4)Nuclear receptors:These receptors are named not just for their locations,but also for their mode of activation.1) Ion channel receptors: Include ligand‐gated ion channels and voltage‐gated ion channels 2) G protein‐coupled receptors: Largest cell surface receptor family (or “superfamily”). Also termed 7‐TM (transmembrane domain) receptors 3) Kinase‐linked receptors: These receptors have an extracellular ligand‐binding domain and an intracellular kinase domain 4) Nuclear receptors: These receptors are named not just for their locations, but also for their mode of activation. Classification of receptors (by structure and mode of action)