Lactase, a member of the beta - galactosidase enzyme family, hydrolyzes the -(1g4) glycosidic bond in lactose yielding its component - D - galactose and - D - glucose monosaccharides. (appliedhealth.com)
In the picture depicted, one of the two copies of the gene of the mouse was replaced with the lac Z cassette expressing the bacterial beta galactosidase and its activity in the kidney is followed by staining. (thevalleefoundation.org)
A. Bartesaghi et al. 2.2 Å resolution cryo - EM structure of β - galactosidase in complex with a cell - permeant inhibitor. (sciencenews.org)