Signalling and Receptor

Signalling and Receptor

1. RECEPTORS

   • What are they?
     • Receptor are proteins found on the plasma membrane or inside cells
   • How do they work?
     • Positive Physiological Response = Agonist Ligand Negative Physiological Response = Antagonist Ligand
   • Types
     • Enzyme- coupled Receptors
       • Ligand attaches to receptor
       • Two receptors join together (dimerization)
       • Enzymatic reaction (induced or direct)
         • Kinases
           • Phoshorylates -OH on serine, threonine and tyrsoine in proteins
         • Phoshphatases
         • GTPase
           • GEF
           • GAP
         • RTK
         • MAP Kinase
     • G-Protein coupled
     • Channel
   • Inactivation of Receptors
     • Engulfed, ligand leaves receptor, ligand broken down, receptor recycled
     • Direct inactivation e.g using phosphotases
     • Negative Feedback

2. MODES OF CELL SIGNALLING

   • Paracrine
     • A cell excretes ligand which effects neiighbouring cells as it spreads out by diffusion
   • Endocrine
     • Ligand excerted into blood stream
   • Synaptic
     • Neurotransmitters between neurone
   • Contact Dependant

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