Low molecular weight storage material in infantile ceroid lipofuscinosis (CLN1)

The identification of the genetic defect in CLN1 as a palmitoyl-protein thioesterase deficiency initiated a search for the lysosomal storage material. Pulse-chase labelling of fibroblasts and lymphoblastoid cell lines with [35S]cysteine revealed the presence of lipid [35S]cysteine material in CLN1 fibroblasts and not in controls, CLN2 or CLN3 patients or other patients with lipidosis. A single band comigrated with the acylcysteine standard and labelling with [3H]palmitate showed a band of material which eluted from the silicic acid column with the phospholipid fraction and which co-migrated with the lipid-[35S]cysteine band. The storage material is tentatively identified as palmitoylcysteine.