I-SMAD BMP2:BMP type II receptor:Phospho-BMP type I receptor:I-SMAD BMP:BMPRII:P-BMPRI I-Smad competes with R-Smad1/5/8 for type I receptor Authored: Huminiecki, L, Moustakas, A, 2007-11-07 10:22:00 Edited: Jassal, B, 2007-08-13 08:42:05 I-SMADs reside in the nucleus presumably to be sequestered from the BMP2:receptor complex and thus avoid inappropriate silencing of the signalling pathway. Upon activation of the signalling pathway, I-SMADs exit the nucleus and are recruited to the signalling BMP2:receptor complex. I-SMADs directly bind to the so-called L45 loop of the type I receptor, the site of binding of R-SMADs. Thus, I-SMADs competitively inhibit the activation/phosphorylation of R-SMADs. Pubmed12519765 Pubmed12857866 Reactome Database ID Release 43201475 Reactome, http://www.reactome.org ReactomeREACT_115888 Reviewed: Heldin, CH, 2007--1-1-