Where are lysosomal enzymes made?

Lysosomal enzymes are synthesized by proteins in the endoplasmic reticulum and are then transported to the Golgi apparatus. They are delivered to the Golgi apparatus through transport vesicles and then become tagged for lysosomes through the addition of mannose-6-phosphate. Once budding occurs from the Golgi network, lysosomes are formed with the mannose-6-phosphate label packaged into them. Errors made during formation of lysosomal enzymes may cause lysosomal storage diseases such as Pompe’s disease and Tay-Sachs disease.