Transcriptional modulator activated by BMP (bone morphogenetic proteins) type 1 receptor kinase. SMAD1 is a receptor-regulated SMAD (R-SMAD) (By similarity). Has been shown to be also activated by TGF-beta (transforming growth factor) type I receptor kinase in rat intestinal epithelial cells (IEC 4-1). SMAD1/OAZ1/PSMB4 complex mediates the degradation of the CREBBP/EP300 repressor SNIP1.
Specificity
Natural and recombinant Rat Mothers against decapentaplegic homolog 1
Subcellular Location
Cytoplasm Nucleus In the cytoplasm in the absence of ligand. Migration to the nucleus when complexed with SMAD4. Co-localizes with LEMD3 at the nucleus inner membrane.
May form trimers with another SMAD1 and the co-SMAD SMAD4. Interacts with PEBP2-alpha subunit, CREB-binding protein (CBP), NANOG, p300, SMURF1, SMURF2, HOXC8 and HGS. Associates with ZNF423 or ZNF521 in response to BMP2 leading to activate transcription of BMP target genes. Interacts with SKOR1 and ZCCHC12. Interacts (via MH2 domain) with LEMD3. Binding to LEMD3 results in at least a partial reduction of receptor-mediated phosphorylation (By similarity). Forms a ternary complex with PSMB4 and OAZ1 before PSMB4 is incorporated into the 20S proteasome.