SMAD Family

1. SMAD Family Smad family members have been found only in animals. Within the animal kingdom they have been identified in eumetazoans (multicellular organisms with many types of cells) but not yet in metazoans such as sponges (multicellular organisms with very few cell types). However, several transmembrane receptors with similarity to both type I and type II TGF-β receptors have been identified in a freshwater sponge. A phylogenetic analysis showed that the sponge receptors are very similar to the unusual C. elegans receptors DAF-1 and SMA-6 that also fall between receptor types. The similarity between sponge and nematode receptors suggests that Smad-like proteins will eventually be found in sponges. Thus, ancestral TGF-β family members and their signaling pathways predate the metazoan/eumetazoan divergence roughly 1.5 billion years ago. Members of SMAD family Table 1. SMAD family related products SMAD1 SMAD2 SMAD3 SMAD Ligands SMAD3L SMAD4 SMAD5 SMAD6 SMAD7 SMAD9 SMAD1  Mothers against decapentaplegic homolog 1 also known as SMAD family member 1 or SMAD1 is a protein that in humans is encoded by the SMAD1 gene. The Smad1/Mad subfamily contains signal transducing R-Smads dedicated to DPP/BMP subfamily ligands. This protein mediates the signals of the bone morphogenetic proteins (BMPs), which are involved in a range of biological activities including cell growth, apoptosis, morphogenesis, development and immune responses.

2. Figure 1. Structure of the SMAD1 protein. SMAD2  Mothers against decapentaplegic homolog 2 also known as SMAD family member 2 or SMAD2 is a protein that in humans is encoded by the SMAD2 gene. SMAD2 mediates the signal of the transforming growth factor (TGF)- beta, and thus regulates multiple cellular processes, such as cell proliferation, apoptosis, and differentiation. This protein is recruited to the TGF-beta receptors through its interaction with the SMAD anchor for receptor activation (SARA) protein. SMAD3  Mothers against decapentaplegic homolog 3 also known as SMAD family member 3 or SMAD3 is a protein that in humans is encoded by the SMAD3 gene. SMAD3 is a polypeptide with a molecular weight of 48,080 Da. It belongs to the SMAD family of proteins. SMAD3 is recruited by SARA (SMAD Anchor for Receptor Activation) to the membrane, where the TGF-β receptor is located. The receptors for TGF-β, (including nodal, activin, myostatin and other family members) are membrane serine/threonine kinases that preferentially phosphorylate and activate SMAD2 and SMAD3. Based on its essential role in TGF beta signaling pathway, SMAD3 has been related with tumor growth in cancer development. https://www.creative-diagnostics.com/smad-family.htm