Activin A/AB/B:ACVR2A/B:p-ACVR1B Activin A/AB/B:ACVR2A/B:ACVR1B ACVR2A/B (ActRIIA/B) Phosphorylates ACVR1B (ActRIB, ALK4) in Response to Activin Authored: May, B, 2011-01-23 EC Number: 2.7.11 Edited: May, B, 2011-03-03 Pubmed11117535 Pubmed15123686 Pubmed8622651 Pubmed8721982 Pubmed9459292 Reactome Database ID Release 431181149 Reactome, http://www.reactome.org ReactomeREACT_111068 Reviewed: Chen, Ye-Guang, 2012-11-14 Reviewed: Peng, C, 2011-08-24 Upon binding Activin A (INHBA:INHBA), Activin AB (INHBA:INHBB), or Activin B (INHBB:INHBB), the type II component of the activin receptor (ACVR2A or ACVR2B) phosphorylates the type I component ACVR1B (ALK4) at multiple serine and threonine residues within the GS domain (Attisano et al. 1996, Willis et al. 1996, Willis and Mathews 1997, Zhou et al. 2000). has a Stoichiometric coefficient of 12