EXT1:EXT2 transfers GlcA to heparan (R-HSA-2076392) [Homo sapiens]


Exostosin 1 and 2 (EXT1 and 2) are dual specificity enzymes which catalyze the addition of N-acetylglucosamine (GlcNAc) and glucuronate (GlcA) to the GAG protein linker sequence. The first addition mediated by these enzymes is that of glucuronate after EXTL1 has added the first GlcNAc unit to the linkage sequence. EXT1 and 2 form a heterodimer which translocates to the Golgi apparatus from the ER membrane (McCormick et al. 2000). Defects in EXT1 or 2 cause the hereditary bone disorders multiple exostoses type 1 (MIM:133700) and 2 (MIM:133701) (Wuyts et al. 1998, Bernard et al. 2001).

Locations in the PathwayBrowser
Additional Information
Compartment Golgi membrane , Golgi lumen
Components of this entry
Input entries
Output entries
Catalyst Activity
PhysicalEntity Activity Active Units
EXT1:EXT2 N-acetylglucosaminyl-proteoglycan 4-beta-glucuronosyltransferase activity (0050509)  
Literature References
pubMedId Title Journal Year
11169766 Diminished levels of the putative tumor suppressor proteins EXT1 and EXT2 in exostosis chondrocytes Cell Motil Cytoskeleton 2001
10639137 The putative tumor suppressors EXT1 and EXT2 form a stable complex that accumulates in the Golgi apparatus and catalyzes the synthesis of heparan sulfate Proc Natl Acad Sci U S A 2000
9463333 Mutations in the EXT1 and EXT2 genes in hereditary multiple exostoses Am J Hum Genet 1998
Inferred Entries
Orthologous events