New insights into the mechanisms of activin action and inhibition

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Like other members of the transforming growth factor-β (TGF-β) superfamily, activins are synthesised as precursor molecules comprising an N-terminal prodomain and C-terminal mature region. During synthesis, the prodomain interacts non-covalently with mature activin, maintaining the molecule in a conformation competent for dimerisation. Dimeric precursors are cleaved by proprotein convertases and activin is secreted from the cell non-covalently associated with its propeptide. Extracellularly, the propeptide interacts with heparan sulfate proteoglycans to regulate activin localization within tissues. The mature activin dimer exhibits the classic 'open-hand' structure of TGF-β ligands with 'finger-like' domains projecting outward from the cysteine knot core of the molecule. These finger domains form the binding epitopes for type I and II serine/threonine kinase receptors. Activins ability to access its signalling receptors is regulated by the extracellular binding proteins, follistatin, follistatin-like-3, and by inhibins, which, in the presence of betaglycan, sequester type II receptors.

Original languageEnglish
Pages (from-to)2-12
Number of pages11
JournalMolecular and Cellular Endocrinology
Issue number1-2
Publication statusPublished - 15 Aug 2012
Externally publishedYes


  • Activin
  • Betaglycan
  • Follistatin
  • Inhibin
  • Prodomain
  • Transforming growth factor-β

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