Cell-Signalling

• Cell-Signalling

  • Cell-cell recognition and communication
  • Triggered to work together
  • Actions co-ordinated to trigger response in cells
  • (Target) Cells respond to environmental signals
  • Receptors (protein or glycoproteins)
  • Receptor
  • Specific complementary shape to signalling molecule
  • Binding triggers response
  • Some (e.g. hydrophilic proteins) only bind surface (e.g. insulin)
  • Others (e.g. hydrophobic steroids) diffuse in, bind intracellular, often on DNA
  • Signalling molecule
  • Immediate change cell metabolism or electrical charge (e.g. action potential)
  • Or gene expression (transcription)
• Types:

  • Hormones
  • Released from endocrine gland
  • Transported by blood
  • Specific complementary receptors
  • Binding cause event sequence in target cell
  • Cytokines; paracrine signalling
  • Chemicals released by cells into tissue fluid
  • Act locally
  • Immune response
  • Macrophages as APCs
  • Communicate w/ T + B lymphocytes
  • Neurotransmitters; neuronal
  • Over synapse to remote cell
  • Cell-Cell contact
  • Direct contact w/ adjacent cells’ surface molecules
  • Proteins, glycoproteins or glycolipids

  Many signal molecules for different signalling types

  Crucial differences lie in signal speed + selectivity