G- Couple Protein Receptors

STRUCTURE
1. Extra cellular part then snake like part spanning within the membrane
2. Consists of another part called the G-protein which is made out of three part (alpha, beta and gamma)
3. Has Two Parts
HOW DOES IT WORK? (Pathway 1)
1. Ligand messenger attaches to the extraceullar part, activating the alpha subunit of the g-protein
2. The GDP attached to the alpha subunit is exchanged for a GTP
  1. Can be inactivated using GTPase
3. The Alpha subunit detaches from both the gamma and beta subunit, acivating both parts
  1. The is leads to adenylyl cyclase forming cAMP (using ATP)
    1. The adenylyl cyclase removes two phosphates from the ATP forming cAMP
      1. The cAMP effect can be deactivated by using cAMP phosphodiesterase which adds water onto cAMP forming 5'-AMP
4. Formation of cAMP leads to activation of protein kinase A which can phosphorylate multiple targets such as transcription factors
They can operate channels
1. Directly
  1. Bind as ligands to channel
2. Indirectly
  1. Activate molecules which effect channels eg IP3
HOW DOES IT WORK? (Pathway 2)
1. The signal molecule attaches to the GCPR
  1. The causes the alpha subunit to exchange GDP for GTP
    1. The alpha subunit dissociates from the beta and gamma subunit
      1. This leads to the activation of Phospholipase C
        The activation of protein kinase C leads to the cleaving of PI 4,5 biphosphate into IP3 and diacylglycerol
        IP3 causes the ER to release Calcium ions by binding to Calcium Ion channels
        Meanwhile Diacylglycerol actviates Protein Kinase C
        The calcium ions can also then activate Protein Kinase C aswell as calmodulin
        Calmodulin can also activate calmodulin dependant kinases which tweak the synapse

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G- Couple Protein Receptors

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	Created by Has Maj over 8 years ago