RECEPTORS AND TRANSDUCTION 1:
IONOTROPIC RECEPTORS!
THESE LECTURES ARE MCQ NOT ESSAY
STYLE
OVERVIEW OF RECEPTOR-MEDIATED
NEUROTRANSMISSION BY IONOTROPIC
RECEPTORS, WITH EXAMPLES OF:
1) NICOTINIC ACETYLCHOLINE
RECEPTOR
2) GLUTAMATE RECEPTORS
RECEPTORS ARE CATEGORISED BASED ON THEIR
TRANSDUCTION MECHANISMS
THIS RESPONSE OUTPUT OCCURS THROUGH RECEPTORS THAT ARE LOCATED ON
THE POST-SYNAPTIC MEMBRANE
THESE FAST-ACTING MOLECULAR SWITCHES ARE OLIGOMERIC PROTEINS
COMPOSED OF TWO MAIN FUNCTIONAL PARTS: AN EXTRACELLULAR, LIGAND-
BINDING DOMAIN, AND A GATED,
MEMBRANE-SPANNING PORE.
THE MAIN DIFFERENCE BETWEEN
RECEPTORS IS THE WAY IN WHICH NTS
COUPLE TO THEM, AND THE SUBSEQUENT
RESPONSE
IONOTROPIC RECEPTORS
DIRECTLY COUPLED TO ION CHANNELS
ACTIVATED BY NEUROTRANSMITTERS WHICH
OPEN THE CHANNEL PORE TO ALLOW
MOVEMENT OF SPECIFIC IONS, CREATING
POSTSYNAPTIC POTENTIALS.
LIGAND-GATED OR VOLTAGE-GATED
ELICIT A FASTER RESPONSE
METABOTROPIC RECEPTORS
THESE RECEPTORS ARE NOT DIRECTLY COUPLED TO THEIR ION CHANNELS AND
, TRANSDUCE THE SIGNAL VIA GUANYL NUCLEOTIDE-BINDING PROTEINS (G-
PROTEINS) THAT ACTIVATE INTRACELLULAR SECOND MESSENGER PATHWAYS
MOST IMPORTANT NT IN THE MAMMALIAN BRAIN:
• GLUTAMATE AND GABA ARE THE MOST ABUNDANT NT WHICH MEDIATE
SYNAPTIC TRANSMISSION IN THE CNS VIA IONOTROPIC RECEPTORS
IN GENERAL,
• GABA – INHIBITORY (DAMPEN POST-SYNAPTIC SIGNAL) WHEREAS
• GLUTAMATE – EXCITATORY (MAINTAIN POST-SYNAPTIC TRANSMISSION)
IONOTROPIC RECEPTORS: STRUCTURAL FEATURES
RECEPTOR TYPES – STRUCTURAL
OVERVIEW
GLUTAMATE CAN WORK AS A NT FOR 3
MAIN TYPES OF IONOTROPIC RECEPTORS:
AMPA, NMDA KAINATE. THESE
AND
ARE ALL TETRAMERIC RECEPTORS:
ASSEMBLED FROM 3 SUBUNITS.
ACETYLCHOLINE IS A NT FOR
PENTAMERIC RECEPTORS (CONSIST OF 5
SUBUNITS). WITHIN THE NACH
RECEPTOR, THE ALPHA AND BETA
SUBUNITS HAVE SEVERAL DIFFERENT TYPES, AND ANY ONE OF THESE CAN MAKE
UP THE PENTAMERIC RECEPTOR.
ASSEMBLIES OF RECEPTORS FORM DIFFERENT FUNCTIONAL UNITS IN DIFFERENT
REGIONS OF THE NERVOUS SYSTEM.
CAN ALSO BE ASSEMBLED FROM SIMILAR SUBUNITS (HOMOMERIC) OR DIFFERENT
SUBUNITS (HETEROMERIC)
1) NICOTINIC ACETYLCHOLINE
RECEPTOR (NACHR)
IONOTROPIC RECEPTORS!
THESE LECTURES ARE MCQ NOT ESSAY
STYLE
OVERVIEW OF RECEPTOR-MEDIATED
NEUROTRANSMISSION BY IONOTROPIC
RECEPTORS, WITH EXAMPLES OF:
1) NICOTINIC ACETYLCHOLINE
RECEPTOR
2) GLUTAMATE RECEPTORS
RECEPTORS ARE CATEGORISED BASED ON THEIR
TRANSDUCTION MECHANISMS
THIS RESPONSE OUTPUT OCCURS THROUGH RECEPTORS THAT ARE LOCATED ON
THE POST-SYNAPTIC MEMBRANE
THESE FAST-ACTING MOLECULAR SWITCHES ARE OLIGOMERIC PROTEINS
COMPOSED OF TWO MAIN FUNCTIONAL PARTS: AN EXTRACELLULAR, LIGAND-
BINDING DOMAIN, AND A GATED,
MEMBRANE-SPANNING PORE.
THE MAIN DIFFERENCE BETWEEN
RECEPTORS IS THE WAY IN WHICH NTS
COUPLE TO THEM, AND THE SUBSEQUENT
RESPONSE
IONOTROPIC RECEPTORS
DIRECTLY COUPLED TO ION CHANNELS
ACTIVATED BY NEUROTRANSMITTERS WHICH
OPEN THE CHANNEL PORE TO ALLOW
MOVEMENT OF SPECIFIC IONS, CREATING
POSTSYNAPTIC POTENTIALS.
LIGAND-GATED OR VOLTAGE-GATED
ELICIT A FASTER RESPONSE
METABOTROPIC RECEPTORS
THESE RECEPTORS ARE NOT DIRECTLY COUPLED TO THEIR ION CHANNELS AND
, TRANSDUCE THE SIGNAL VIA GUANYL NUCLEOTIDE-BINDING PROTEINS (G-
PROTEINS) THAT ACTIVATE INTRACELLULAR SECOND MESSENGER PATHWAYS
MOST IMPORTANT NT IN THE MAMMALIAN BRAIN:
• GLUTAMATE AND GABA ARE THE MOST ABUNDANT NT WHICH MEDIATE
SYNAPTIC TRANSMISSION IN THE CNS VIA IONOTROPIC RECEPTORS
IN GENERAL,
• GABA – INHIBITORY (DAMPEN POST-SYNAPTIC SIGNAL) WHEREAS
• GLUTAMATE – EXCITATORY (MAINTAIN POST-SYNAPTIC TRANSMISSION)
IONOTROPIC RECEPTORS: STRUCTURAL FEATURES
RECEPTOR TYPES – STRUCTURAL
OVERVIEW
GLUTAMATE CAN WORK AS A NT FOR 3
MAIN TYPES OF IONOTROPIC RECEPTORS:
AMPA, NMDA KAINATE. THESE
AND
ARE ALL TETRAMERIC RECEPTORS:
ASSEMBLED FROM 3 SUBUNITS.
ACETYLCHOLINE IS A NT FOR
PENTAMERIC RECEPTORS (CONSIST OF 5
SUBUNITS). WITHIN THE NACH
RECEPTOR, THE ALPHA AND BETA
SUBUNITS HAVE SEVERAL DIFFERENT TYPES, AND ANY ONE OF THESE CAN MAKE
UP THE PENTAMERIC RECEPTOR.
ASSEMBLIES OF RECEPTORS FORM DIFFERENT FUNCTIONAL UNITS IN DIFFERENT
REGIONS OF THE NERVOUS SYSTEM.
CAN ALSO BE ASSEMBLED FROM SIMILAR SUBUNITS (HOMOMERIC) OR DIFFERENT
SUBUNITS (HETEROMERIC)
1) NICOTINIC ACETYLCHOLINE
RECEPTOR (NACHR)
