Mothers against decapentaplegic homolog 9

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SMAD, Mothers against decapentaplegic homolog 9
Other names:	SMAD 9, Mothers against DPP homolog 9, Smad9, Madh6
Genetic data
Gene code:	HUGO code:SMAD9
Protein Structure/Function
Protein type:	R-SMAD
Functions:	signal transduction, transcription
Domains:	MH1, MH2
Other
Taxa expressing:	homo sapiens; homologs: many metazoan phyla
Cell types:	many; heart, brain, placenta, lung, skeletal muscle, prostate, testis, ovary and small intestine
Subcellular localization:	Primary:nucleus, Alternative:cytoplasm
Covalent modifications:	phosphorylation

SMAD9 or Mothers against decapentaplegic homolog 9 is a polypeptide that, as its name describes, is a homolog of the Drosophila gene: "Mothers against decepentaplegic". It belongs to the SMAD family of proteins, which belong to the TGFβ superfamily of modulators. Like many other TGFβ family members, SMAD9 is involved in cell signalling. When a bone morphogenetic protein binds to a receptor (BMP type 1 receptor kinase) it causes SMAD9 to interact with SMAD anchor for receptor activation (SARA).The binding of ligands causes the phosphorylation of the SMAD9 protein and the dissociation from SARA and the association with SMAD4. It is subsequently transferred to the nucleus where it forms complexes with other proteins and acts as a transcription factor. SMAD9 is a receptor regulated SMAD (R-SMAD) and is activated by bone morphogenetic protein type 1 receptor kinase. There are two isoforms of the protein.

Identifiers
Symbol	SMAD9 MADH2, MADR2
HUGO	6774
Entrez	4093
OMIM	603295
RefSeq	NM_005905
UniProt	O15198
Other data
Locus	Chr. 13 q12-q14

[edit] Nomenclature

The SMAD proteins are homologs of both the drosophila protein, mothers against decapentaplegic (MAD) and the C. elegans protein SMA. The name is a combination of the two. During Drosophila research, it was found that a mutation in the gene, MAD, in the mother, repressed the gene, decapentaplegic, in the embryo. The phrase "Mothers against" was added since mothers often form organizations opposing various issues eg. Mothers Against Drunk Driving or (MADD).