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JCGG-STR003511 JCGG-STR033554
JCGG-STR027299 JCGG-STR033555
JCGG-STR033556 JCGG-STR033557
JCGG-STR003511 JCGG-STR033551
JCGG-STR003511 JCGG-STR033551
JCGG-STR033552 JCGG-STR033553
EXTL 2 encodes exostosin-like glycosyltransferase 2. This gene belongs to multiple exostoses (EXT) family and is involved in heparan sulfate and heparin biosynthesis. The main structure of heparan sulfate is a disaccharide repeating structure consisting of (GlcNAcα1-4GlcAβ1-4) and EXTL2 isα1,4-N-acetylglucosaminyltransferase that transfers GlcNAc to the non-reducing terminal of GlcA by the α1,4 bond mainly during chain length extension process.
It transfers the first GlcNAc to the glycosaminoglycan-protein binding region (linkage tetrasaccharide structure: GlcAb1-3Gabl1-3Galb1-4Xylb1-O-Ser) which is the basic skeleton of glycosaminoglycan, and the key enzyme (Initiation enzyme: GlcNAcT-I), which is the starting point of the disaccharide repeat structural synthesis, competes with the synthetase of the chondroitin sulfate and dermatan sulfate biosynthesized on the same linkage tetrasaccharide structure. Transfer of the first GlcNAc by this GlcNAcT-I leads to promotion of biosynthesis of heparan sulfate and heparin. Since EXTL2 shows GlcNAc transferring activity against the analog sugar substrate of linkage tetrasaccharide (GlcAb1-3Gabl1-O-naphthalenemethanol, GlcAb1-3Gabl1-O-C2H4NHCbz), it is suggested that it may have GlcNAcT-I activity.
In addition, it has also been reported that in “in vitro” substrate specificity analysis, this enzyme shows activity that transfers N-acetylgalactosamine (GalNAc) to the linkage tetrasaccharides (GlcAb1-3Gabl1-3Galb1-4Xylb1-O-Ser) etc. Through the experiments that change the expression of EXTL2 gene, it is suggested that EXTL2 functions as a chain terminator of HS and may influence the elongation of heparan sulfate and heparin.
Other genes from EXT family also have glycosyltransferase activity related to synthesis of both the heparan sulfate and heparin, but unlike EXT 1, EXT 2, etc., no association with Hereditary multiple exostoses (HME) has been reported for EXTL2. Meanwhile, in Sanfilippo C syndrome, it is reported that the EXTL2 (and EXTL3) gene is useful as a target of its treatment (therapeutic drug development).

Heparan Sulfate Heparin

N-Acetylgalactosaminyltransferase N-Acetylglucosaminyltransferase

Alias EXTR2    details
Designationheparan sulfate a4-N-Acetylhexosaminyltransferase, glucuronyl-galactosyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase/alpha-1,4-N-acetylgalactosaminyltransferase
OrganismHomo sapiens
GeneID 2135
HGNC 3516
mRNA NM_001439       (CDS)
Protein NP_001430       (CDS)
CAZy GT64   
OMIM 602411   
This page does not indicate all of the enzymatic reaction, and expression of "EXTL2".