Their membranes contain hydrogen ion pumps and chloride ion channel proteins that maintain an interior pH of about 4.8, ideal for their proteasomes and other hydrolytic enzymes.  
A prolonged fast can activate a selective pathway in these structures that involves KFERQ proteins.  I-cell disease results from a defect in the addition of the mannose-6-phosphate moiety used to target enzymes to them, and a deficiency of the enzyme glucocerebrosidase ("gloo-coh-ser-eh-BRO-sih-dase") in these organelles leads to Gaucher's ("go-SHAYZ") disease.  Their membranes contain hydrogen ion pumps and chloride ion channel proteins that maintain an interior pH of about 4.8, ideal for their proteasomes and other hydrolytic enzymes.  Autophagy occurs in, FTP, these organelles responsible for enzymatic digestion of cell components and ingested matter.
A prolonged fast can activate a selective pathway in these structures that involves KFERQ proteins.  
lysosomes