Immunocytochemical localization of lysosomal beta-galactosidase in rat liver.

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Abstract
.beta.-galactosidase is a ubiquitous lysosomal hydrolase that specifically cleaves terminal .beta.-galactosyl residues from glycoproteins, glycosaminoglycans, oligosaccharides and glycolipids. To study the intracellular distribution of this enzyme, a specific polyclonal antibody to lysosomal .beta.-galactosidase was prepared by immunizing rabbits with a highly purified preparation of .beta.-galactosidase from rat liver. This antibody was used in an immunocytochemical technique (protein A coupled to horseradish peroxidase and diaminobenzidine cytochemistry) which showed that .beta.-galactosidase is present in all hepatocytes of the rat liver. All types of lysosomes, the rough endoplasmic reticulum and the specialized region of smooth endoplasmic reticulum known as GERL showed immunoreactivity. This in situ distribution suggests that these organelles are involved in the biosynthesis and intracellular sorting of this lysosomal enzyme.