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RECEPTOR PHARMACOLOGY
GENERAL ASPECTS OF RECEPTOR PHARMACOLOGY
STRUCTURAL AND FUNCTIONAL ASPECTS OF RECEPTORS
BY
Mahender....
RECEPTOR
 A receptor is a molecule most often found on the
surface of a cell, which receives chemical signals
originating...
Targets for drug action
 Receptors are protein molecules, embedded in either the
plasma membrane (cell surface receptors) or the
cytoplasm or nuc...
 Numerous receptor types are found within a typical cell
and each type is linked to a specific biochemical
pathway.
 Fur...
CLASSIFICATION:
 By Modality and adequate stimulus
 Mechanical input - mechanoreceptors (touch, pressure, stretching, mo...
LIGAND-GATED ION CHANNELS
 Ligand-gated ion channels (LGICs) are one type of ionotropic
receptor or channel-linked recept...
STRUCTURE:
 The five receptor sub units (2α,β,γ,δ) form a cluster
surrounding a central transmembrane pore, the
lining is formed by ...
G PROTEIN-COUPLED RECEPTOR
 It consists of a single polypeptide chain of up to
1100 residues.
 Their characteristic stru...
FUNCTION
 It consists of three sub units which are anchored to the
membrane through attached lipase residues.
 Coupling of the al...
KINASE LINKED RECPTORS
 These mediate the action of wide variety of protein
mediators including growth factors, cytokines...
 Receptors of various growth factors incorporate tyrosine
kinase in their intracellular domain.
 Cytokine receptors have...
NUCLEAR RECEPTORS
 Two main categories
o those that are present in the cytoplasm form homodimers
in the presence of their...
THANK YOU
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  1. 1. RECEPTOR PHARMACOLOGY GENERAL ASPECTS OF RECEPTOR PHARMACOLOGY STRUCTURAL AND FUNCTIONAL ASPECTS OF RECEPTORS BY Mahender.K M.Pharm 1st yr 2nd sem. Srikrupa institute of pharmaceutical sciences, Velkatta,kondapak,medak. Andhra pradesh. Under the guidance of Dr. T.Shivaraj gouda M.pharm.,PhD H.O.D. (Pharmacology)
  2. 2. RECEPTOR  A receptor is a molecule most often found on the surface of a cell, which receives chemical signals originating externally from the cell.  Through binding to a receptor, these signals direct a cell to do something—for example to divide or die, or to allow certain molecules to enter or exit.
  3. 3. Targets for drug action
  4. 4.  Receptors are protein molecules, embedded in either the plasma membrane (cell surface receptors) or the cytoplasm or nucleus (nuclear receptors) of a cell, to which one or more specific kinds of signaling molecules may attach.  A molecule which binds (attaches) to a receptor is called a ligand, and may be a peptide (short protein) or other small molecule, such as a neurotransmitter, a hormone, a pharmaceutical drug, or a toxin.
  5. 5.  Numerous receptor types are found within a typical cell and each type is linked to a specific biochemical pathway.  Furthermore each type of receptor recognizes and binds only certain ligand shapes (in analogy to a lock and key where the lock represents the receptor and the key, its ligand).  Hence the selective binding of specific a ligand to its receptor activates or inhibits a specific biochemical pathway.
  6. 6. CLASSIFICATION:  By Modality and adequate stimulus  Mechanical input - mechanoreceptors (touch, pressure, stretching, movements)  Electromagnetic - photoreceptors (light)  Chemoreceptors (taste, smell, oxygen level)  Thermoreceptors (cold, warmth)  Electrical – electroreceptors  By Overall function  Exteroreceptors - cutaneously located, responsible for providing information from the immediate environment  Telereceptors - sense events that originate at some distance from the body (such as in eyes, ears, olfactory receptors)  Interoceptors - respond to stimuli originating in the visceral organs  Proprioceptors - convey information about the relative position of the body parts (located in skeletal muscles, tendons, joints, vestibular apparatus)  Clinical classification  This classification is derived from the pathway by which the primary afferent axons enter the CNS.  Special sensory receptors - served by cranial nerves  Cutaneous receptors - innervated by superficial branches of spinal and cranial nerves  Deep receptors - located in muscles, tendons and joints, served by deeper branches of spinal and cranial nerves  Visceral receptors. - served by afferent axons associated with the autonomic nervous system
  7. 7. LIGAND-GATED ION CHANNELS  Ligand-gated ion channels (LGICs) are one type of ionotropic receptor or channel-linked receptor. They are a group of transmembrane ion channels that are opened or closed in response to the binding of a chemical messenger (i.e., a ligand),such as a neurotransmitter.  The binding site of endogenous ligands on LGICs protein complexes are normally located on a different portion of the protein (an allosteric binding site) compared to where the ion conduction pore is located.  The direct link between ligand binding and opening or closing of the ion channel, which is characteristic of ligand-gated ion channels, is contrasted with the indirect function of metabotropic receptors, which use second messengers. LGICs are also different from voltage-gated ion channels (which open and close depending on membrane potential), and stretch-activated ion channels (which open and close depending on mechanical deformation of the cell membrane)
  8. 8. STRUCTURE:
  9. 9.  The five receptor sub units (2α,β,γ,δ) form a cluster surrounding a central transmembrane pore, the lining is formed by M2 hellical segment of each subunit.  These contains a preponderance of negatively charged amino acids , which makes the pore cation selective.  There are two Ach binding sites in the extracellular portion of the receptor, at the interface between the alpha and the adjoining sub units.  When two Ach binds the α helices swing out of the way thus opening the channel pore.
  10. 10. G PROTEIN-COUPLED RECEPTOR  It consists of a single polypeptide chain of up to 1100 residues.  Their characteristic structure consists of 7 trans membrane alpha helicessimilar to those of ion channels, with an extracellular N terminal domain of varying length and intracellular C terminal domain.
  11. 11. FUNCTION
  12. 12.  It consists of three sub units which are anchored to the membrane through attached lipase residues.  Coupling of the alpha sub unit to an agonist occupied receptor causes the bound GDP to exchange with intracellular GTP the alpha GTP complex then dissociates from the receptor and from the beta gamma complex and interacts with a target protein(target 1), which may also activate a target protein(target 2) .  The GTPase activity of the alpha sub unit is increased when the target protein is bound,leading to hydrolysis of the bound GTP to GDP where upon the alpha sub unit reunites with beta gamma.
  13. 13. KINASE LINKED RECPTORS  These mediate the action of wide variety of protein mediators including growth factors, cytokines and hormones such as insulin and leptin whose effects are exercted mainly at the level of gene transcription.  These are large proteins consisting of single chain up to 1000 residues with a single membrane spannig helical region assosiated with a large extracellular ligand binding domain and intracellular kinase domain.
  14. 14.  Receptors of various growth factors incorporate tyrosine kinase in their intracellular domain.  Cytokine receptors have an intracellular domain that binds and activates cytosolic kinase when the receptor is occupied.  Signal transduction generally involves dimerisation of receptors, followed by autophosporylation of tyrosine residues. The posphotyrosine residues acts as acceptors for SH2domains of intra cellular proteins,there by allowing control of many cell functions,
  15. 15. NUCLEAR RECEPTORS  Two main categories o those that are present in the cytoplasm form homodimers in the presence of their partner, and migrate to the nucleus. Their ligands are endocrine in nature (eg:steroidal hormones). o those that are generally present in the nucleus and form heterodimers with the retenoid X receptor. Their ligands are usually lipids.(eg:fatty acids) o third sub group tranduce mainly endocrine signals but function as heterodimers with retenoid X receptor .(eg:thyroid hormone)  The receptor family is responsible for the pharmacology of appx.10% and pharmacokinetics of 60% of all prescribed drugs.
  16. 16. THANK YOU

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