Exostosin1 and 2 (EXT1 and 2) are dual specificity enzymes which catalyze the addition of N acetylglucosamine (GlcNAc) and glucuronate (GlcA) to extend the GAG chain on the protein linker sequence. Heparan is synthesized once GlcNAc is transferred to this 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).
|EXT1:EXT2||glucuronosyl-N-acetylglucosaminyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase activity (0050508)|
|11169766||Diminished levels of the putative tumor suppressor proteins EXT1 and EXT2 in exostosis chondrocytes||Cell Motil Cytoskeleton||2001|
|9463333||Mutations in the EXT1 and EXT2 genes in hereditary multiple exostoses||Am J Hum Genet||1998|
|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|