GPCRs

GPCRs

Structure?
1. 7 trans-membrane domains
2. are trimeric g-proteins: alpha, beta and gamma subunits.
  1. The G-alpha subunit is commonly responsible for most biological effects
3. are guanine nucleotide-binding proteins
Activation?
1. Bind guanine-diphosphate (GDP) in inactive state. Bind guanine-triphosphate (GTP) in their active state.
2. can be stimulatory or inhibitory
3. 1. G- protein rests in its inactive state, bound to GDP
  1. 2. When the receptor is activated, the G-protein exchanges GDP for GTP. On binding to the 1st messenger, there is a conformational change in the 7 transmembrane receptor.
    1. 3. The activated G-protein splits and the G-alpha and G-beta-gamma subunits are now available to activate effector proteins.
      1. 4. The G-alpha subunit slowly hydrolyses GTP to GDP, terminating it's own activity and becoming inactive again. So, the GPCR 'times itself'.
Roles?
1. To couple receptors...
  1. ...effectors which catalyze formation of second messengers
  2. ...directly to ion channels
  3. to 3 main effector pathways:
    1. 1. Direct-Effector Linked Pathway
    2. 2. Adenylyl Cyclase Pathway
    3. 3. Phospholipase-C Pathway
2. control whether we feel pain, or feel happy.
Effects of Activation may include:
1. Metabolic Changes
2. Movement
3. Cell Death
4. Transcription
5. Protein Synthesis

Resource summary

	Created by Sophie Barrett about 10 years ago