FunctionAntagonist 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 specificityUbiquitous in various organs, with higher levels in lung. Isoform B is up-regulated in diseased heart tissue.
Sequence similaritiesBelongs to the dwarfin/SMAD family. Contains 1 MH1 (MAD homology 1) domain. Contains 1 MH2 (MAD homology 2) domain.
Post-translational modificationsPhosphorylated by BMP type 1 receptor kinase and by PRKX. Ubiquitinated by WWP1.