I-SMAD:SMURF BMP:p-BMPR:I-SMAD:SMURF BMP:BMPRII:P-BMPRI I-Smad binds to type I receptor, preventing Smad1/5/8 from being activated Authored: Huminiecki, L, Moustakas, A, 2007-11-07 10:22:00 Pubmed11278251 Pubmed12151385 Pubmed12857866 Reactome Database ID Release 43201821 Reactome, http://www.reactome.org ReactomeREACT_12013 Reviewed: Heldin, CH, 2007--1-1- Smad6 and Smad7, the two I-Smads, bind directly to the BMP type I receptors and recruit the ubiquitin ligase Smurf1. This reaction leads to competitive inhibition of R-Smad binding to the type I receptor and activating phosphorylation by the receptor, and also leads to BMP receptor ubiquitination and degradation.