Beta-galactosidase 1 (GLB1)

Beta-galactosidase 1 (GLB1) is a lysosomal enzyme encoded by the GLB1 gene in humans, classified in the glycoside hydrolase 35 (GH35) family[1][4][8]. It catalyzes the hydrolysis of terminal non-reducing β-D-galactose residues from gangliosides, glycoproteins, and glycosaminoglycans, playing a key role in cellular catabolism and recycling of complex carbohydrates[1][3][4]. Its physiological substrates include GM1 ganglioside—crucial for normal neuronal function—and keratan sulfate—abundant in cartilage and cornea[1]. Deficiency of beta-galactosidase 1, due to GLB1 mutations, leads to lysosomal storage disorders such as GM1 gangliosidosis and Morquio B disease, characterized by neurodegeneration and/or skeletal abnormalities[1][8]. GLB1 activity is a critical biomarker for diagnosing and monitoring these diseases, and therapies aim to restore enzyme function or compensate for its loss[1]. There are no established small-molecule drugs targeting GLB1 directly, but gene and enzyme replacement therapies are in clinical development.

Other names

Galactosidase beta 1β-galactosidasebeta-D-galactoside galactohydrolaseEC 3.2.1.23

Substrate hydrolysis leading to breakdown of GM1 ganglioside and keratan sulfate. In enzyme replacement therapy, as an exogenous enzyme supplement that restores lysosomal function in deficient individuals.