GLB1 substrates Defective GLB1 does not hydrolyse Gal Authored: Jassal, B, 2012-05-21 Defective GLB1 does not hydrolyse galactose from KS or GAG linker chain Defects in beta-galactosidase (GLB1, MIM:611458) result in galactose moieties not being hydrolysed from keratan sulfate (KS) or the GAG linker chain, a tetrasccharide sequence required for some GAG biosyntheses to take place. Mucopolysaccharidosis IV B (MPSIVB, Morquio's syndrome B; MIM:253010) is the result of GLB1 deficiency.<br>GLB1 mutations causing severe phenotypes are R482C (Ishii et al. 1995), W509C (Oshima et al. 1991), Y83C (Santamaria et al. 2006) and W273L Paschke et al. 2001. Mild phenotypes where a partial loss of enzyme activity occurs can involve the mutants G438E, N484K, T500A (Bagshaw et al. 2002) and Y83H (Ishii et al. 1995). These mild phenotype mutants are not detailed here. Edited: Jassal, B, 2012-05-21 Pubmed11511921 Pubmed12393180 Pubmed16941474 Pubmed1928092 Pubmed7586649 Reactome Database ID Release 432265534 Reactome, http://www.reactome.org ReactomeREACT_147709 Reviewed: Alves, Sandra, 2012-08-27 Reviewed: Coutinho, Maria, 2012-08-27