Natural and synthetic factors that influence the metabolism of the simple sphingolipids will be investigated. Compounds resembling sphingosine and ceramide will be tested in vitro as potential inhibitors of cerebroside and ceramide biosynthesis. A protein partially purified from bovine spleen will be studied to determine the mechanism by which it speeds the uptake of glucocerebroside by membranes, starting with labeled vesicles containing cerebroside, lecithin, and cholesterol. A different protein from bovine spleen that stimulates the enzyme, glucosidase, will be studied similarly. Antibodies will be prepared to the active proteins to develop a quantitative or qualitative assay for them in tissues, partly to see if their concentrations in tissues can be correlated with cerebroside metabolism. Ceramide and glucocerebroside levels in tissues will be measured to see what factors influence them.