CR1:C3bBb, C4bC2a complexes C4bC2a, C3bBb CR1 binds C3bBb/C4bC2a Authored: Jupe, S, 2010-10-26 Complement Receptor 1 (CR1) is a widely distributed cell surface protein that is a decay accelerating factor for the conventional (C4bC2a) and alternative (C3bBb) C3 convertases (Coico & Sunshine 2009). Edited: Jupe, S, 2010-11-01 Pubmed293688 Reactome Database ID Release 43977375 Reactome, http://www.reactome.org ReactomeREACT_118580 Reviewed: Bradley, DT, 2012-02-13 Reviewed: Fraczek, LA, 2012-02-13 has a Stoichiometric coefficient of 2