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Regulation of activin type I receptor function by phosphorylation of residues outside the GS domain

S A Willis1, L S Mathews

  • 1Department of Biological Chemistry, University of Michigan, Ann Arbor 48109-0606, USA.

FEBS Letters
|February 12, 1998
PubMed

Activin signals through a heteromeric complex of receptor serine kinases by inducing type II receptor-mediated phosphorylation, and consequent activation, of the type I receptor. Type I receptor phosphorylation occurs at a glycine- and serine-rich site in the juxtamembrane domain; phosphorylation at that site correlates with signaling. Investigation of type I activin receptor mutants impaired for GS domain phosphorylation revealed that, in the presence of elevated amounts of type II activin receptor, GS domain phosphorylation is not required for signaling. The type I receptor showed activin-dependent phosphorylation of several tryptic phosphopeptides, suggesting that phosphorylation of receptor I at sites both within and outside the GS domain is required for full signaling.

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