Information on EC 2.4.1.224 - glucuronosyl-N-acetylglucosaminyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase and Organism(s) Drosophila melanogaster and UniProt Accession Q9Y169
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Involved in the biosynthesis of heparin and heparan sulfate. Some forms of the enzyme from human (particularly the enzyme complex encoded by the EXT1 and EXT2 genes) act as bifunctional glycosyltransferases, which also have the 4-beta-glucuronosyltransferase (EC 2.4.1.225, N-acetylglucosaminyl-proteoglycan 4-beta-glucuronosyltransferase) activity required for the synthesis of the heparan sulfate disaccharide repeats. Other human forms of this enzyme (e.g. the product of the EXTL1 gene) have only the 4-alpha-N-acetylglucosaminyltransferase activity. In Caenorhabditis elegans, the product of the rib-2 gene displays the activities of this enzyme as well as EC 2.4.1.223, glucuronosyl-galactosyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase.
Involved in the biosynthesis of heparin and heparan sulfate. Some forms of the enzyme from human (particularly the enzyme complex encoded by the EXT1 and EXT2 genes) act as bifunctional glycosyltransferases, which also have the 4-beta-glucuronosyltransferase (EC 2.4.1.225, N-acetylglucosaminyl-proteoglycan 4-beta-glucuronosyltransferase) activity required for the synthesis of the heparan sulfate disaccharide repeats. Other human forms of this enzyme (e.g. the product of the EXTL1 gene) have only the 4-alpha-N-acetylglucosaminyltransferase activity. In Caenorhabditis elegans, the product of the rib-2 gene displays the activities of this enzyme as well as EC 2.4.1.223, glucuronosyl-galactosyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase.
EXT isozymes are localized mainly in the cis- and middle-Golgi stacks. Rotini, Rti, mediates the retrograde transport of EXT enzymes within the Golgi complex
EXT isozymes are localized mainly in the cis- and middle-Golgi stacks. Rotini, Rti, mediates the retrograde transport of EXT enzymes within the Golgi complex. Rotini regulates the sub-compartmental distribution of EXTs in the Golgi
mutations in the tumor suppressor genes EXT1 and EXT2 disturb heparan sulfate proteoglycan biosynthesis and cause multiple osteochondroma. A reduction in Rti shifts the steady-state distribution of EXTs to the trans-Golgi. These accumulated EXTs tend to be degraded and their re-entrance towards the route for polymerizing GAG chains is disengaged. Conversely, EXTs are mislocalized towards the transitional endoplasmic reticulum/cis-Golgi when Rti is overexpressed. Both loss of function and overexpression of rti result in incomplete heparan sulfate proteoglycans and perturb Hedgehog signaling
exostosin (EXT) genes encode glycosyltransferases required for glycosaminoglycan chain polymerization in the biosynthesis of heparan sulfate proteoglycans. Synthesis of heparan sulfate proteoglycans requires sequential enzymatic modifications of glycoproteins in the Golgi. Drosophila Golgi phosphoprotein 3, GOLPH3 or rotini, Rti, regulates the biosynthesis of heparan sulfate proteoglycans by modulating the retrograde trafficking of exostosins. Rti regulates the stability of EXTs
mutations in the tumor suppressor genes EXT1 and EXT2 disturb heparan sulfate proteoglycan biosynthesis and cause multiple osteochondroma. A reduction in Rti shifts the steady-state distribution of EXTs to the trans-Golgi. These accumulated EXTs tend to be degraded and their re-entrance towards the route for polymerizing GAG chains is disengaged. Conversely, EXTs are mislocalized towards the transitional endoplasmic reticulum/cis-Golgi when Rti is overexpressed. Both loss of function and overexpression of rti result in incomplete heparan sulfate proteoglycans and perturb Hedgehog signaling
exostosin (EXT) genes encode glycosyltransferases required for glycosaminoglycan chain polymerization in the biosynthesis of heparan sulfate proteoglycans. Synthesis of heparan sulfate proteoglycans requires sequential enzymatic modifications of glycoproteins in the Golgi. Drosophila Golgi phosphoprotein 3, GOLPH3 or rotini, Rti, regulates the biosynthesis of heparan sulfate proteoglycans by modulating the retrograde trafficking of exostosins. Rti regulates the stability of EXTs. Proper function of EXTs depends not only on their enzymatic activities but also on their sub-compartmental distributions
Kim, B.T.; Kitagawa, H.; Tamura, J.I.; Kusche-Gullberg, M.; Lindahl, U.; Sugahara, K.
Demonstration of a novel gene DEXT3 of Drosophila melanogaster as the essential N-acetylglucosamine transferase in the heparan sulfate biosynthesis: Chain initiation and elongation