Topic 74 - Membrane receptor signaling Flashcards

1
Q

Words to include

A
  • Transduction
  • G-protein independent
  • Transmembraen protein
  • Ligand binding part
  • Central part
  • Inner part
    • Phosphorylase activity
  • Ligand bond
  • IC peptide chain phosphorylase
  • Nicotinic acetylcholine receptor
    • Ion channel-forming transmembrane protein
    • CNS
    • PNS
    • Conformational change
    • Cation channel
    • Local excitatory potential
    • Action potential
  • Glutamate-sensitive receptors
    • Post-synaptic membrane-integrated cation channel
    • Glutamate antagonists
      • NMDA receptor (N-metil-D-asparate)
        • Mg2+ dissociation receptor
      • AMPA receptor
      • Kainate-receptor
  • Anion receptor
    • Anion channels
    • Inhibitory synapses
    • CNS
    • Mediators
      • GABA (Gamma Amino Butyric Acid)
        • GABA-A receptor
          • Ionotropic
        • GABA-B receptor
          • Metabotropic
      • Glycine
      • IC cAMP
      • K+ channels
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2
Q

General

A
  • Transduction = G-protein independent
  • Receptor may be a special transmembrane protein of 3 parts:
    1. Ligand binding part (on EC side)
    2. Central part (passes through membrane)
    3. Inner part (on IC side – protein continues and exhibits phosphorylase activity)
  • Ligand bond on outer surface IC peptide chain phosphorylates/activates receptor or cellular proteins biological action

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3
Q

Name the membrane receptors

A
  1. Nicotinic acetylcholine receptor (n-Ach-R)
  2. Glutamate-sensitive receptors
  3. Anion receptors
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4
Q

Nicotinic actylcholine receptor (N-Ach-R)

A
  • Ion-channel-forming transmembrane protein
  • Found in CNS and PNS
  • In closed state before binding of ACh
  • Binding of ACh → conformational changes → opening of cation channel (open state)
  • Influx of cations (e.g. Na+) local excitatory potential and stimulation of action potential
  • Channel returns to closed state after dissociation of ligand
  • Family with 5 membrane-integrated (transmembrane) domains
    • Subunits in skeletal muscle:
      • 2 α subunits (Ach binding site)
      • 2 β subunits
      • 1 Δ subunit
    • Subunits in nervous tissue: (insensitive to curare)
      • 2 α subunits (Ach binding site)
      • 3 β subunits
  • The whole receptor serves as an ion channel​
  • Ligand binding site (EC side)
  • The receptor can be inhibited by d-tubocurarine (curare)
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5
Q

Glutamate-sensitive receptors

A
  • Post-synaptic membrane-integrated cation channel
  • 3 main groups according to glutamate antagonists:
    1. NMDA receptor (N-metil-D-aspartate)
      • Binding of Mg2+ keeps the receptor closed
      • Mg2+ dissociatied after receptor activation
    2. AMPA receptor
    3. Kainate-receptor
  • Glutamate also binds to various metabotropic receptors
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6
Q

Anion receptors

A
  • Opening of anion channels important in inhibitory synapses of CNS
  • 2 main mediators:
    1. GABA (Gamma Amino Butyric Acid)
      • Acts on GABA-A (ionotropic) or GABA-B (metabotropic)
      • GABA-B decreases IC cAMP and effects K+ channels
    2. Glycine
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