Acid Ceramidase: A ceramidase subtype that is active at acid pH. It plays an important role in sphingolipid degradation by catalyzing the lysosomal hydrolysis of ceramide to sphingosine and free fatty acid. Inherited deficiency of acid ceramidase activity results in FARBER LIPOGRANULOMATOSIS.Galactosylgalactosylglucosylceramidase: An enzyme that catalyzes the hydrolysis of a ceramidetrihexoside to a ceramidedihexoside plus galactose.Neutral Ceramidase: A ceramidase subtype that is active at neutral pH. It is found at high levels within the SMALL INTESTINE and in the BRAIN.Ceramidases: Amidohydrolases that are specific for the cleavage of the N-acyl linkage of CERAMIDES. Ceramidases are classified as acidic, neutral or basic according to the optimal pH with which they function.Alkaline Ceramidase: A ceramidase subtype that is active at alkaline pH. It is found at high levels within the SMALL INTESTINE.Farber Lipogranulomatosis: A sphingolipidosis subtype that is characterized by the histological appearance of granulomatous deposits in tissues. It results from the accumulation of CERAMIDES in various tissues due to an inherited deficiency of ACID CERAMIDASE.Ceramides: Members of the class of neutral glycosphingolipids. They are the basic units of SPHINGOLIPIDS. They are sphingoids attached via their amino groups to a long chain fatty acyl group. They abnormally accumulate in FABRY DISEASE.AmidohydrolasesSphingosine: An amino alcohol with a long unsaturated hydrocarbon chain. Sphingosine and its derivative sphinganine are the major bases of the sphingolipids in mammals. (Dorland, 28th ed)Sphingolipids: A class of membrane lipids that have a polar head and two nonpolar tails. They are composed of one molecule of the long-chain amino alcohol sphingosine (4-sphingenine) or one of its derivatives, one molecule of a long-chain acid, a polar head alcohol and sometimes phosphoric acid in diester linkage at the polar head group. (Lehninger et al, Principles of Biochemistry, 2nd ed)Myristates: Salts and esters of the 14-carbon saturated monocarboxylic acid--myristic acid.Sphingomyelin Phosphodiesterase: An enzyme that catalyzes the hydrolysis of sphingomyelin to ceramide (N-acylsphingosine) plus choline phosphate. A defect in this enzyme leads to NIEMANN-PICK DISEASE. EC Activator Proteins: A family of glycoprotein cofactors that are required for the efficient catabolization of SPHINGOLIPIDS by specific acid hydrolases such as GLUCOSYLCERAMIDASE; GALACTOCEREBROSIDASE; BETA-N-ACETYLHEXOSAMINIDASE; and CEREBROSIDE-SULFATASE.Monoglycerides: GLYCEROL esterified with a single acyl (FATTY ACIDS) chain.Lysosomal Storage Diseases: Inborn errors of metabolism characterized by defects in specific lysosomal hydrolases and resulting in intracellular accumulation of unmetabolized substrates.Lysophospholipids: Derivatives of PHOSPHATIDIC ACIDS that lack one of its fatty acyl chains due to its hydrolytic removal.Dolichol Phosphates: Phosphoric acid esters of dolichol.Saposins: A group of four homologous sphingolipid activator proteins that are formed from proteolytic cleavage of a common protein precursor molecule referred to as prosaposin.