This gene encodes a lysosomal serine protease that cleaves N-terminal tripeptides from protein substrates. The encoded preproprotein undergoes autocatalytic processing to generate a mature enzyme. Mice lacking the encoded protein exhibit a progressive neurodegeneration and a greatly shortened lifespan. At the cellular level, mice lacking the encoded protein exhibit accumulation of autofluorescent lipopigments. Mutations in the human ortholog of this gene cause classical late-infantile neuronal ceroid lipofuscinosis. [provided by RefSeq, Nov 2015]