MHC II alpha beta heterodimer alpha beta dimer:Ii trimer:calnexin Nonameric complex Formation of nonameric complex Authored: Garapati, P V, 2012-02-21 Edited: Garapati, P V, 2012-02-21 Progressive addition of two more preformed alpha beta dimers to the invariant chain trimer and alpha beta complex ((alpha beta)1:(Ii)3) forms the complete nonameric structure ((alpha beta:Ii)3). Calnexin then disassociates on egress of the nonameric complex from the ER. Pubmed16618111 Pubmed1956401 Pubmed9312039 Reactome Database ID Release 432213241 Reactome, http://www.reactome.org ReactomeREACT_120846 Reviewed: Neefjes, Jacques, 2012-05-14 has a Stoichiometric coefficient of 2