Antagonist of signaling by TGF-beta (transforming growth factor) type 1 receptor superfamily members, has been shown to inhibit selectively BMP (bone morphogenetic proteins) signaling by competing with the co-SMAD SMAD4 for receptor-activated SMAD1. SMAD6 is an inhibitory SMAD (I-SMAD) or antagonistic SMAD. Binds to regulatory elements in target promoter regions.Tissue specificity: Ubiquitous in various organs, with higher levels in lung. Isoform B is up-regulated in diseased heart tissue.
