SMAD family member 5 (SMAD5)

SMAD5 or Mothers against decapentaplegic homolog 5 is a polypeptide that, as its name describes, is a homolog of the Drosophila gene: "Mothers against decapentaplegic". It belongs to the SMAD family of proteins, which belong to the TGF beta superfamily of modulators. Like many other TGF beta family members SMAD5 is involved in cell signalling and modulates signals of bone morphogenetic proteins (BMP's).

The binding of ligands causes the oligomerization and phosphorylation of the SMAD5 protein. SMAD5 is a receptor regulated SMAD (R-SMAD) and is activated by bone morphogenetic protein type 1 receptor kinase. It may play a role in the pathway where TGF beta is an inhibitor of hematopoietic progenitor cells.