receptors
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biochemistry and pharmacology, receptors are chemical structures, composed of protein, that receive and transduce signals that may be integrated into biological systems
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receptors
- 1. Receptor Presented By: Mr Vijay Salvekar Associate Professor Dept. of Pharmacology GRY Institute of Pharmacy,Borawan
- 2. Receptor A receptor is a protein molecule usually found embedded within the plasma membrane surface of a cell that receives chemical signals from outside the cell and when such chemical signals bind to a receptor, they cause some form of cellular/tissue response.
- 3. WHAT IS ARECEPTOR? â˘Specialized areas of cell to which drugs get bound. â˘They are regulatory protein macro molecules . â˘Drug should have âselectivity to a receptor ; receptor should have ligand specificity to elicit action.
- 4. RECEPTOR CLASSIFICATION 1. Inotropic. 2. Metabotropic. 3. Ligand regulated trans membrane. 1. Nuclear receptors . Cell surface Intracellular 7
- 5. Classification There are 2 types of receptors. Those are : Internal & Cell surface receptor. i. Internal /Intracellular/Cytoplasmic receptors : ďź found in the cytoplasm of the cell ďź respond to hydrophobic ligand molecules
- 6. Internal receptor : Internal /Intracellular Receptors : ďźHydrophobic signaling molecules typically diffuse across the plasma membrane ďźinteract with intracellular receptors in the cytoplasm. 5
- 8. Cell surface receptor ii. Cell-surface /transmembrane receptors/cell- specific proteins ďź performs signal transduction, converting an extracellular signal into an intracellular signal. 3 main components: i. External ligand-binding domain (extracellular domain) ii. Hydrophobic membrane-spanning region iii. Intracellular domain inside the cell 6
- 9. Cell surface receptor There are three general categories of cell-surface receptors: ⢠Inotropic. Ion channel-linked receptors, Ligand gated ion channel Direct alter membrane potential ⢠Metabotropic G-protein-linked receptors, Enzyme-linked receptors.
- 12. Ion Channel-Linked Receptors ďź Receptors bind with ligand. (Ex:Nicotinic Receptor) ďź Open a channel through the membrane that allows specific ions to pass through. ďźConformational change in the protein's structure that allows ions such as Na,Ca, Mg, and H2 to pass through.
- 13. ION CHANNELS - IMPORTANCE ⢠Generation , propagation of nerveimpulse. ⢠Synaptic transmission ofneurons. ⢠Muscle contraction. ⢠Salt balance. ⢠Hormone release. ⢠Muscle relaxants , anti-arrhythmatics ,anesthetics â act by blocking ion channels.
- 14. MOLECULAR STRUCTURE â˘ligand binding site in extracellular domain. â˘4 subunits Îą, β, Îł and δ. â˘Îą2, β, Îł - pentameric str - 2 ligand binding sites â˘Each subunit spans the membrane 4 times; all subunits form a central pore.
- 16. RECEPTORS @ VPC
- 22. G-Protein Linked Receptors ďźBinds with a ligand and activate a membrane protein called a G-protein. ďź The activated G-protein then interacts with either an ion channel or an enzyme in the membrane. ďźEach receptor has its own specific extracellular domain and G-protein-binding site. Example : Beta-adrenergic receptor
- 23. ď˘ metabotropic or 7-transmembrane-spanning (heptahelical) receptors. ď˘ coupled to intracellular effector systems via a G-protein. ď˘ mAChRs, adrenoceptors, dopamine, 5-HT, opiate, peptide, purinoceptors, orphans . 17
- 25. FAMILIES OF GPCR 3 families: ď˘ A â rhodopsin family eg. Amine NT, purines , cannabinoids ď˘ B - secretin/glucagon receptor family Eg. Peptide hormones. ď˘ C - metabotropic glutamate receptor/calcium sensor family. Eg. GABAB, Glutamate. 19
- 26. G-PROTEIN -ROLE ď˘ Membrane resident proteins â recognize activated GPCRs- pass message to effector system. ď˘ Occurs in interaction with guanine nucleotides ; freely moving in cytoplas ď˘ Îą, β and Îł subunits â trimer in resting state. ď˘ 3 subunits attached to GPCR through fatty acid chain â reaction called prenylation. 20
- 27. Enzyme-Linked Receptors ďźCell surface receptors with intracellular domains that are associated with an enzyme. ďźNormally have large extracellular and intracellular domains. ďźWhen a ligand binds to the extracellular domain, a signal is transferred through the membrane and activates the enzyme, which eventually leads to a response. Example : Tyrosine Kinase receptor