Storage of saposins A and D in infantile neuronal ceroid-lipofuscinosis.

We have isolated storage cytosomes from brain tissue of patients with infantile neuronal ceroid-lipofuscinosis. The purified storage bodies were subjected to compositional analysis which revealed a high content of proteins, accounting for 43% of dry weight. Saposins A and D, also known as sphingolipid activator proteins (SAPs), were shown to constitute a major portion of the accumulated protein using gel electrophoresis and sequence analysis. This is the first time that saposins have been found to be stored in any form of neuronal ceroid-lipofuscinosis.