Palmitoyl-protein thioesterase and the molecular pathogenesis of infantile neuronal ceroid lipofuscinosis.

Palmitoyl-protein thioesterase (PPT) has recently been shown to be the defective enzyme underlying the infantile form of neuronal ceroid lipofuscinosis (INCL). In this paper, we review the enzymology of PPT, evidence for its localization in lysosomes, and recent advances in understanding the metabolic defect caused by PPT deficiency. Absence of PPT activity in lysosomes isolated from INCL lymphoblasts is demonstrated. A model for the formation of the storage bodies in INCL involving defective autophagocytic proteolysis is proposed.