Beta-galactosidase is an exoglycosidase which hydrolyzes the beta-glycosidic bond formed between a galactose and its organic moiety. Deficiencies in the protein in humans can result in galactosialidosis or Morquio B syndrome. In E. coli, the gene of beta-galactosidase, the lacZ gene, is present as part of the inducible system lac operon, which is activated in the presence of lactose when glucose level is low. E. coli beta-galactosidase is commonly used in molecular biology as a reporter marker to monitor gene expression. Another popular use for beta-galactosidase is in blue/white screening to identify recombinant clones. Beta-galactosidase can be split into two peptides, lacZalpha and LacZOmega, neither of which is active by itself but when both are present together, spontaneously reassemble into a functional enzyme. This property is exploited in many cloning vectors. The presence or absence of an active beta-galactosidase may be detected through addition of artificial chromogenic substrates such as X-gal, fluorescent substrates such as Fluorescein di-beta-D-galactopyranoside (FDG), luminescent substrates, and others. Beta-galactosidase activity at pH 6 is an indicator of senescent cells not found in presenescent, quiescent or dividing cells.
b-gal fusion protein; Beta-Gal; beta-gal fusion protein; betagal; bgal; ß-gal; ß-galactosidase; ßgal