The gene ASAH1 encodes the enzyme N-acylsphingosine amidohydrolase or acid ceramidase, which catalyzes the synthesis and degradation of ceramide into sphingosine and fatty acids within lysosomes. The resulting sphingosine undergoes phosphorylation to generate sphingosine-1-phosphate (S1P). Ceramide, sphingosine, and S1P are bioactive lipids that are involved in numerous cellular processes including cell growth arrest, differentiation, stress responses and apoptosis. Upon translation, a heterodimeric protein consisting of a nonglycosylated alpha subunit and a glycosylated beta subunit is produced. This protein undergoes posttranslational cleavage giving rise to the mature enzyme. A number of transcript variants encoding several distinct isoforms have been identified.