Receptors and its classification

1. RECEPTOR TYPES
 CHANNEL LINKED (IONOTROPIC)
 G PROTEIN LINKED (METABOTROPIC)
 ENZYME LINKED
 INTRACELLULAR RECEPTOR
(RECEPTORS REGULATING GENE TRANSCRIPTION
/NUCLEAR RECEPTORS)

3. CHANNEL LINKED (IONOTROPIC) :
The cell surface has a selective ion channel like Na, K , Ca , or Cl .
 Onset of action through these types of receptors is fastest –
milliseconds.
 Nicotinic cholinergic receptors, GABA-A and NMDA receptors.
Cl-influx
Hyperpolarisation of neuronal
membrane(> -90mv)
-70 mv
Antianxiety, General
anaesthesia, Anticonvulsant
effects

4. G PROTEIN LINKED (METABOTROPIC) :
These are cell membrane receptors which are linked to effector
mechanisms through G-proteins.
 Effector mechanisms includes adenylyl cyclase, phospholipase C
 Onset of response in seconds.
 Eg : adrenergic receptors, histamine receptors

5. MECHANISMS: Through IP3-DAG
pathway
G-Protein receptors

6. Through C-AMP pathway

7. ENZYME LINKED(Kinase linked)
These cell membrane receptors are enzymatic in nature
 Insulin acts through this receptors.
 Onset of response in minutes.

8. INTRACELLULAR RECEPTOR
These includes
Steroids, Thyroxine and Vit–D
It takes days to produce its actions
(RECEPTORS REGULATING GENE
TRANSCRIPTION/NUCLEAR RECEPTORS)

9. Classification of ion channels
 Gating mechanism
 Leakage channels
 Voltage –gated channels
 Ligand –gated channels
 Ions transported
 Ca2+
ion channels
 Na+
ion channels
 Cl-
ion channels
 K+
ion channels

10.  Inhibitory function.
 Nicotinic cholinergic
 GABA-A
 Glycine
 Excitatory function
 NMDA
 kainate

11. G-PROTEIN COUPLED RECEPTORS:-
1. Adrenergic receptors
2. Cholinergic receptors
3. Seretonergic receptors
4. Dopaminergic receptors
5. Histaminergic receptors
6. GABA/BZ-receptors
7. Excitatory amino acid receptors
8. Opioid receptors
9. Purinergic receptors

12. 1)ADRENERGIC RECEPTORS
I α & β-ADRENERGIC RECEPTORS
 α -ADRENERGIC RECEPTORS
a) α -1RECEPTORS
b) α -2 RECEPTORS
2 β RECEPTORS
a) β -1RECEPTORS
b) β -2 RECEPTORS
c) β -3 RECEPTORS

13. 2)CHOLINERGIC RECEPTORS
 THERE ARE 2 TYPES OF RECEPTORS
 MUSCARINIC RECEPTORS
a)M-1
b)M-2
c)M-3
 NICOTINIC RECEPTORS
a)NM
b)NN
c)NN1
d)NN2

14. 3) SERETONERGIC (5-HT) RECEPTORS
1) 5-HT-1
2)5 HT-2
3)5 HT-3
4)5 HT-4

15. 4) DOPAMINERGIC RECEPTORS
 THERE ARE 2 CLASSES
1)D1-Receptors
2)D2-Receptors

16. 5) HISTAMINERGIC RECEPTORS
 There are 2 types
1)H1-Receptors
2)H2- Receptors

17. 6) GABA RECEPTORS
 Three different types of GABA-Receptors
are:-
1)GABAA
2)GABAB
3)GABAC

18. 7)EXCITATORY AMINO ACID
RECETORS :-
 These are of 4 types:-
1)NMDA
2)AMPA
3)Kainate
4)Metabotropic

19. 8) OPIOID RECEPTORS
 There are 3 types in this are:-
1)µ-Opioid Receptors
2)κ-Opioid Receptors
3)δ-Opioid Receptors

20. 9)PURINERGIC RECEPTORS
 There are 2 types in this are:-
1)p1(adenosin receptors)
2)p2(adenosin triphoshate/ATP receptors)