TGFB1:TGFBR2:p-TGFBR1 TGFB1:p-TGFBR:I-SMAD7 I-SMAD competes with SMAD2/3 for type I receptor (TGFBR1) Authored: Heldin, CH, Moustakas, A, Huminiecki, L, Jassal, B, 2006-02-02 Edited: Jassal, B, 2006-02-10 14:02:35 Edited: Jassal, B, 2012-04-10 GENE ONTOLOGYGO:0030512 I-SMADs (SMAD6 and SMAD7) reside in the nucleus presumably to be sequestered from the TGF-beta receptor complex and thus avoid inappropriate silencing of the signaling pathway. Upon activation of the signaling pathway, I-SMADs exit the nucleus and are recruited to the signaling TGF-beta 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. Pubmed9215638 Pubmed9335507 Reactome Database ID Release 43173512 Reactome, http://www.reactome.org ReactomeREACT_6909 Reviewed: Heldin, CH, 2006-04-18 14:26:12 Reviewed: Huang, Tao, 2012-05-14