G Protein Coupled Receptors (as a system)

Heterotrimeric G Proteins
1. Gs Family
  1. Activate adenylate cyclase
  2. regulate PKA, protein kinase A
2. Gi Family
  1. i = inhibit
  2. inhibit adenylate cyclase
3. Gq Family
  1. q.. P.. r s etc
    1. i.e. P comes after Q
  2. activates Phospholipase C
  3. regulates PKC and IP3
PKA
1. B adrenoceptor activation by adrenaline
2. In heart cAMP increases strength and rate of heart rate (B1)
3. In lungs cAMP relaxes bronchial smooth muscle (B2)
B Adrenoceptors
1. Agonists in the lung
  1. Salbutamol
    1. B2 selective
    2. dilates bronchial smooth muscle, eases respiration
    3. used in asthma
2. Antagonists in the heart
  1. B1 Selective
  2. Atenolol
    1. competitive reversible antagonist
    2. slows heart rate, reduces force of beat
A Adrenoceptors
1. Activated by epinephrine
2. related to Gq family
3. IP3 releases Ca2+ from the sacroplasmic reticulum
  1. DAG opens Ca2+ channel
    1. Ca2+ flows
      1. increase in Ca2+ at intracellular level
4. Pharmacology of A1 adrenoceptor
  1. Prazosin
    1. competitive, reversible antagonist at a1 adrenoceptor
      1. Prevents contraction of SM in blood vessel wall
        Blood vessels dilate so BP falls
Receptor Tyrosine Kinases (RTKs)
1. Tyrosine Kinase definition
  1. an enzyme that can transfer a phosphate group to a tyrosine residue in a protein
2. Tyrosine kinase coupled receptors
  1. found on cell membrane
  2. receptors for hormones/growth factors
  3. express tyrosine kinase activity
  4. combine to form dimers
  5. affect cell metabolistm

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G Protein Coupled Receptors (as a system)

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	Created by Laura Young about 11 years ago