Classification of receptors family by vivek sharma

Definition- Receptor are the biologic molecule to which drug bind and produces a measurable response.
So, enzyme and structural proteins can be considerd to be pharmacologic receptors.
Majorly receptor are of 4 types and the molecule or a drug interact to receptor to give response often called as ligand.
The type of receptor a ligand will bind is depend on the nature of ligand.
Hydrophilliic ligand binds to the receptor found on the cell surface.
Hydrophobic ligand can enter the cell membrane to intract the receptor present on inside the cells.
Classification of Receptors
A. Cell surface receptor
Ligand-gated Ion Channel
G Protein Coupled Receptor
Enzyme linked Receptor
B. Intracellular Receptor
Nuclear Receptor

1. Classification of Receptors Family By Vivek Sharma M. Pharmacy 1 st sem Department-Pharmacology

2. TOPICS INTRODUCTION TYPES Functioning of cell surface receptor Ligand gated ion channel G protein coupled receptor Enzyme linked receptor Intracellular receptor Refrence

3. INTRODUCTION Definition - Receptor are the biologic molecule to which drug bind and produces a measurable response . So, enzyme and structural proteins can be considerd to be pharmacologic receptors. Majorly receptor are of 4 types and the molecule or a drug interact to receptor to give response often called as ligand . The type of receptor a ligand will bind is depend on the nature of ligand . Hydrophilliic ligand binds to the receptor found on the cell surface. Hydrophobic ligand can enter the cell membrane to intract the receptor present on inside the cells.

4. Example

5. Example

6. Classification of Receptors A. Cell surface receptor Ligand -gated Ion Channel G Protein Coupled Receptor Enzyme linked Receptor B. Intracellular Receptor Nuclear Receptor

7. Cell Surface receptor Cells interact with environment through cell surface receptors.

8. Classification of Cell surface receptors

9. Ligand Gated Ion Channel

10. Conti. Ionotropic receptors - Can be inhibitory and Excitatory and have fast synaptic transmission . Eg - GABAa and Glutamate receptor of NMDA etc. These have switch between OPEN and CLOSED state. The direction of opening and closing is depend upon the Electrochemical gradient of ions. The structure of Ion channels are pentameric contain 2 alpha subunit ,beta, gama and delta . All subunit forms a central pore.

11. Conti.

12. Mecanism of Ion Channel Eg . Response cause by increase or decrease level of ions - Increase sodium and calcium- Excitatory Response Dicrease Sodium and calcium – Inhibitory Response Increase Potassium – Inhibitory Response Increase Chloride – Inhibitory Response

13. Importance of ion channel Synaptic transmission of Neuron Muscle contraction Salt balance Hormone Release While the muscle relaxant, anti arrhythmic drugs and anesthetics act by blocking the ion channels

14. G-Protein Coupled Receptrs Also called metabotropic , transmembrane heptahelical receptor ( because of its structure). Eg . Dopamine, 5-HT,Peptide,Purinoceptors . E Wilson et al described that 800 Human gene codes are in GPCR Family in his review article (2010) Guanine nucleotide or G protein are composed of alpha, beta and gama subunits.

15. .

16. Conti. A number of G Proteins distinguished by their alpha subunit have been described. Gs – Adenylyl Cyclase activation , calcium channel opening Gi – Adenylyl Cylase inhibition , poassium channel opening G0 – Calcium channel inhibition. Gq – Phospholipase C activation .

17. a) Adenylyl Cyclase – cAMP pathway Activation of AC results in intracellular accumulation of second massanger cAMP which function throgh cAMP dependent Protein kinase . cAMP directly opens a no. of calcium channel in heart, brain and kidney which are called cyclic nucleotide gated channel (CNG) The action of cAMP is terminated intracellularly by phosphodiesterase .

18. Conti.

19. b) Phospolipase C IP3 DAG Pathway Binding of Hormone to receptor on cell plasma membrane Which activates trimeric proteins . G alpha subunit activates enzyme associated enzyme phospholipase C. This cause leaving of Phosphotidyl inositol bisphosphate from its lipid tail i.e. Diacylglycerol . Inositol triphosphate and Tail Diacylglycerol act as separate masssanger . While Hormone act as 1 st massanger which produces cellular response.

20. Conti.

21. Channel Regulations The activated G proteins can also open and inhibit ionic channels calcium and potassium without intervention of 2 ndory messengers can also cause HYPERPOLARIZATION and DEPOLARIZATION . Gs- Calcium channel open of Myocardium and skeletal muscle Gi,Go - Potassium channel open of Smooth muscle and Heart.

22. Enzyme linked Receptor

23. Conti. Hormone such as insulin bids to receptor that cause conformational changes. That leads to phosphorylation of tyrosine kinase which is intracellular domain and is innate, intrinsic part but not detached during activation. Then active phosphorylated tyrosine kinase phosphorylates and affect a protein called insulin receptor substance Which turn stimulate cascade of biological Response.

24. Intracellular Receptor These are the receptors which are present inside the cells and perform various functions such as protein sythesis and work by Transcription . The Nuclear receptor comes under this category of receptor in which the sy nthsis of steroidal hormones take place. Eg . Aldosterone and other steroid hormones.

25. Nuclear Receptor

26. Conti. Hormone binds to Carboxy terminal of receptor then the restricting proteins are released (HSP90 etc.) The DNA binding domain folds into requisite configuration . It forms a complex with DNA sequence that cause synthesis of mRNA for specific protein. mRNA moves into cytoplasm and binds to ribosome and the direct synthesis of specific proteins take place .

27. REFRENCES RICHARD’s LIPPINCOTT’s illustrated reviews of PHARMACOLOGY , 4th edition , Page no 25 – 34 KD Tripati , essentials of medical pharmacology ; 6th edition; 2008, 40-52 Popovic , Natasa & Wilson, Emily. (2010). Cell Surface Receptors. 10.1016/B978-0-08-046884-6.00206-2.

28. THANK YOU