Mothers against decapentaplegic homolog 1 also known as SMAD family member 1 or SMAD1 is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

that in humans is encoded by the ''SMAD1''

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

Nomenclature

SMAD1 belongs to the SMAD, a family of proteins similar to the gene products of the ''

Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many speci ...

'' gene '

mothers against decapentaplegic Mothers against decapentaplegic is a protein from the SMAD family that was discovered in ''Drosophila''. During ''Drosophila'' research, it was found that a mutation in the gene in the mother repressed the gene decapentaplegic in the embryo. The ...

' (Mad) and the ''

C. elegans ''Caenorhabditis elegans'' () is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a blend of the Greek ''caeno-'' (recent), ''rhabditis'' (r ...

'' gene Sma. The name is a combination of the two; and based on a tradition of such unusual naming within the gene research community. It was found that a mutation in the 'Drosophila' gene, ''MAD'', in the mother, repressed the gene, ''

decapentaplegic Decapentaplegic (Dpp) is a key morphogen involved in the development of the fruit fly '' Drosophila melanogaster'' and is the first validated secreted morphogen. It is known to be necessary for the correct patterning and development of the early ...

'', in the embryo. Mad mutations can be placed in an allelic series based on the relative severity of the maternal effect enhancement of weak dpp alleles, thus explaining the name Mothers against dpp.

Function

SMAD proteins are signal transducers and transcriptional modulators that mediate multiple signaling pathways. This protein mediates the signals of the

bone morphogenetic protein Bone morphogenetic proteins (BMPs) 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 ...

s (BMPs), which are involved in a range of biological activities including cell growth,

apoptosis Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes ( morphology) and death. These changes in ...

morphogenesis Morphogenesis (from the Greek ''morphê'' shape and ''genesis'' creation, literally "the generation of form") is the biological process that causes a cell, tissue or organism to develop its shape. It is one of three fundamental aspects of deve ...

development Development or developing may refer to: Arts *Development hell, when a project is stuck in development *Filmmaking, development phase, including finance and budgeting *Development (music), the process thematic material is reshaped * Photograph ...

and immune responses. In response to BMP ligands, this protein can be

phosphorylated In chemistry, phosphorylation is the attachment of a phosphate group to a molecule or an ion. This process and its inverse, dephosphorylation, are common in biology and could be driven by natural selection. Text was copied from this source, wh ...

and activated by the BMP receptor kinase. The phosphorylated form of this protein forms a complex with

SMAD4 SMAD4, also called SMAD family member 4, Mothers against decapentaplegic homolog 4, or DPC4 (Deleted in Pancreatic Cancer-4) is a highly conserved protein present in all metazoans. It belongs to the SMAD family of transcription factor proteins, ...

, which is important for its function in the transcription regulation. This protein is a target for SMAD-specific

E3 ubiquitin ligase A ubiquitin ligase (also called an E3 ubiquitin ligase) is a protein that recruits an E2 ubiquitin-conjugating enzyme that has been loaded with ubiquitin, recognizes a protein substrate, and assists or directly catalyzes the transfer of ubiquiti ...

s, such as

SMURF1 E3 ubiquitin-protein ligase SMURF1 is an enzyme that in humans is encoded by the ''SMURF1'' gene. Function This gene encodes a ubiquitin ligase that is specific for receptor-regulated SMAD proteins in the bone morphogenetic protein ( BMP) pat ...

and

SMURF2 E3 ubiquitin-protein ligase SMURF2 is an enzyme that in humans is encoded by the ''SMURF2'' gene which is located at chromosome 17q23.3-q24.1. Interactions SMURF2 has been shown to interact with: * Mothers against decapentaplegic homolog 1, * ...

, and undergoes ubiquitination and

proteasome-mediated degradation Proteasomes are protein complexes which degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds. Enzymes that help such reactions are called proteases. Proteasomes are part of a major mechanism by whi ...

. Alternatively spliced transcript variants encoding the same protein have been observed. SMAD1 is a receptor regulated SMAD (

R-SMAD R-SMADs are receptor-regulated SMADs. SMADs are transcription factors that transduce extracellular TGF-β superfamily ligand signaling from cell membrane bound TGF-β receptors into the nucleus where they activate transcription TGF-β target ge ...

) and is activated by bone morphogenetic protein type 1 receptor kinase.

References

External links

''Drosophila'' ''Mothers against dpp'' - The Interactive Fly
* * {{DEFAULTSORT:Mothers Against Decapentaplegic Homolog 1 Transcription factors Developmental genes and proteins MH1 domain MH2 domain R-SMAD Human proteins