GDP-fucose Protein O-fucosyltransferase 1
Encyclopedia
GDP-fucose protein O-fucosyltransferase 1 (POFUT1) is an enzyme
responsible for adding fucose
sugars in O linkage to serine
or threonine
residues between the second and third conserved cysteines in EGF
-like repeats on the Notch
protein. The protein is an inverting glycosyltransferase
, which means that the enzyme uses GDP-β-L-fucose as a donor substrate and transfers the fucose in O linkage to the protein producing fucose-α-O-serine/threonine.
When the gene for POFUT1 is knocked out, or the expression is decreased to very low levels, all Notch signaling
is destroyed, which means that fucose on Notch is essential for Notch function. Why this is the case is not yet well understood.
Almost all glycosyltransferases reside in the Golgi apparatus
. However, POFUT1 as well as the related enzyme
POFUT2
have recently been shown to reside in the endoplasmic reticulum
.
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
responsible for adding fucose
Fucose
Fucose is a hexose deoxy sugar with the chemical formula C6H12O5. It is found on N-linked glycans on the mammalian, insect and plant cell surface, and is the fundamental sub-unit of the fucoidan polysaccharide...
sugars in O linkage to serine
Serine
Serine is an amino acid with the formula HO2CCHCH2OH. It is one of the proteinogenic amino acids. By virtue of the hydroxyl group, serine is classified as a polar amino acid.-Occurrence and biosynthesis:...
or threonine
Threonine
Threonine is an α-amino acid with the chemical formula HO2CCHCHCH3. Its codons are ACU, ACA, ACC, and ACG. This essential amino acid is classified as polar...
residues between the second and third conserved cysteines in EGF
Epidermal growth factor
Epidermal growth factor or EGF is a growth factor that plays an important role in the regulation of cell growth, proliferation, and differentiation by binding to its receptor EGFR...
-like repeats on the Notch
Notch
Notch may refer to:* The nock of an arrow* Notch , a Hip hop, R&B, reggae, dancehall and reggaeton artist* Notch signaling pathway, a cell signaling system present in most multicellular organisms...
protein. The protein is an inverting glycosyltransferase
Glycosyltransferase
Glycosyltransferases are enzymes that act as a catalyst for the transfer of a monosaccharide unit from an activated nucleotide sugar to a glycosyl acceptor molecule, usually an alcohol....
, which means that the enzyme uses GDP-β-L-fucose as a donor substrate and transfers the fucose in O linkage to the protein producing fucose-α-O-serine/threonine.
When the gene for POFUT1 is knocked out, or the expression is decreased to very low levels, all Notch signaling
Notch signaling
The notch signaling pathway is a highly conserved cell signaling system present in most multicellular organisms.Notch is present in all metazoans, and mammals possess four different notch receptors, referred to as NOTCH1, NOTCH2, NOTCH3, and NOTCH4. The notch receptor is a single-pass...
is destroyed, which means that fucose on Notch is essential for Notch function. Why this is the case is not yet well understood.
Almost all glycosyltransferases reside in the Golgi apparatus
Golgi apparatus
The Golgi apparatus is an organelle found in most eukaryotic cells. It was identified in 1898 by the Italian physician Camillo Golgi, after whom the Golgi apparatus is named....
. However, POFUT1 as well as the related enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
POFUT2
GDP-fucose protein O-fucosyltransferase 2
GDP-fucose protein O-fucosyltransferase 2 is an enzyme responsible for adding fucose sugars in O linkage to serine or threonine residues in Thrombospondin repeats...
have recently been shown to reside in the endoplasmic reticulum
Endoplasmic reticulum
The endoplasmic reticulum is an organelle of cells in eukaryotic organisms that forms an interconnected network of tubules, vesicles, and cisternae...
.