Mothers against decapentaplegic homolog 9
Encyclopedia
Mothers against decapentaplegic homolog 9 also known as SMAD9, SMAD8, and MADH6 is a protein
that in humans is enocoded by the SMAD9 gene.
SMAD9, 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 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. Confusingly, it is also sometimes referred to as SMAD8 in the literature.
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 e.g. Mothers Against Drunk Driving
or (MADD).
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
that in humans is enocoded by the SMAD9 gene.
SMAD9, as its name describes, is a homolog of the Drosophila
Drosophila melanogaster
Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...
gene: "Mothers against decapentaplegic
Mothers against decapentaplegic
Mothers against decapentaplegic is a protein from the SMAD family that was discovered in Drosophila.The SMAD proteins are homologs of both the Drosophila protein "mothers against decapentaplegic" and the C. elegans protein SMA. The name is a combination of the two...
". It belongs to the SMAD
SMAD (protein)
SMADs are intracellular proteins that transduce extracellular signals from transforming growth factor beta ligands to the nucleus where they activate downstream TGF-β gene transcription....
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
Bone morphogenetic protein
Bone morphogenetic proteins are a group of growth factors also known as cytokines and as metabologens . Originally discovered by their ability to induce the formation of bone and cartilage, BMPs are now considered to constitute a group of pivotal morphogenetic signals, orchestrating tissue...
binds to a receptor (BMP type 1 receptor kinase
BMPR1A
The bone morphogenetic protein receptor, type IA also known as BMPR1A is a protein which in humans is encoded by the BMPR1A gene. BMPR1A has also been designated as CD292 .- Function :...
) it causes SMAD9 to interact with SMAD anchor for receptor activation (SARA).The binding of ligands causes the phosphorylation
Phosphorylation
Phosphorylation is the addition of a phosphate group to a protein or other organic molecule. Phosphorylation activates or deactivates many protein enzymes....
of the SMAD9 protein and the dissociation from SARA and the association with SMAD4. It is subsequently transferred to the nucleus
Cell nucleus
In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...
where it forms complexes with other proteins and acts as a transcription factor
Transcription factor
In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...
. SMAD9 is a receptor regulated SMAD
R-SMAD
R-SMAD stands for receptor-regulated SMAD. Smads are transcription factors that transduce extracellular TGF-ß superfamily ligand signaling from cell membrane bound TGF-ß receptors into the nucleus where they activate transcription TGF-ß target genes...
(R-SMAD
R-SMAD
R-SMAD stands for receptor-regulated SMAD. Smads are transcription factors that transduce extracellular TGF-ß superfamily ligand signaling from cell membrane bound TGF-ß receptors into the nucleus where they activate transcription TGF-ß target genes...
) and is activated by bone morphogenetic protein type 1 receptor kinase. There are two isoforms of the protein. Confusingly, it is also sometimes referred to as SMAD8 in the literature.
Nomenclature
The SMAD proteins are homologs of both the drosophila protein, mothers against decapentaplegic (MAD) and the C. elegansCaenorhabditis elegans
Caenorhabditis elegans is a free-living, transparent nematode , about 1 mm in length, which lives in temperate soil environments. Research into the molecular and developmental biology of C. elegans was begun in 1974 by Sydney Brenner and it has since been used extensively as a model...
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
Decapentaplegic
Decapentaplegic is a key morphogen involved in the development of the fruit fly Drosophila melanogaster. It is known to be necessary for the correct patterning of the fifteen imaginal discs, which are tissues that will become limbs and other organs and structures in the adult fly. It has also been...
, in the embryo. The phrase "Mothers against" was added since mothers often form organizations opposing various issues e.g. Mothers Against Drunk Driving
Mothers Against Drunk Driving
Mothers Against Drunk Driving is a non-profit organization in the United States that seeks to stop drunk driving, support those affected by drunk driving, prevent underage drinking, and overall push for stricter alcohol policy...
or (MADD).