Structure, Sythesis & Transport
  • A peptide hormone made of 29 amino acids
  • Formed as a prohormone named pro-glucagon and cleaved to glucagon
  • Key to glucose homeostasis - 'hyperglycaemic catabolic hormone':
  • Actions virtually all in the Liver:
    • Promotes glycogenolysis - low levels
    • Promotes gluconeogenesis - medium levels
    • Promotes lipolysis, fatty acid oxidation, and ketogenesis - high levels
  • Acts synergistically with catecholamines, glucocorticoids, and growth hormone
Mechanism of Action
  • Binds to a specific G protein coupled receptor on the plasma membrane stimulating adenylyl cyclase
  • Results in the phosphorylation and activation of numerous regulatory enzymes and other protein substrates

Stimulated by:

  • Low plasma glucose
  • Sympathetic stimulation

Inhibited by:

  • Raised plasma glucose
  • Somatostatin
  • Raised plasma fatty acid & ketone bodies