Exostoses (multiple)-like 1-3 (EXTL1-3)

Abstract

The exostosin (Ext) tumor suppressor genes Ext1 and Ext2 are associated with hereditary multiple exostoses (HME) and encode bifunctional glycosyltransferases that are essential for polymerization of heparan sulfate (HS) chains, and three subsequently identified Ext-like genes (EXTL1, EXTL2, and EXTL3) show striking sequence similarity to both Ext1 and Ext2 at the nucleotide and amino acid codon levels (Wise et al. 1997). All Ext genes encode type II transmembrane proteins with a short NH2-terminalcytoplasmic tail, and notably, the COOH-terminal catalytic domain of the Ext proteins is most highly conserved, suggesting a conserved function.