CLN3 is a type II transmembrane protein localized in the late endosomal/lysosomal compartment. A deficiency of CLN3 leads to the development of a certain type of Neuronal Ceroid Lipofuscinosis, a neurodegenerative disorder of childhood caused by aggregation of undegraded material in the lysosomal compartment. Cultured, immortalized wild type and Cln3(Δex7/8) cerebellar granule cells were used in this project to determine the influence of Cln3 deficiency on the proteome of the lysosomal compartment. For this purpose, cells were labelled by stable amino acid labelling in cell culture and lysosomes were isolated by magnetic beads.