Extracellular trehalose, a disaccharide, is cleaved by trehalase associated with the plasma membrane to yield two molecules of glucose. Trehalase has been purified to homogeneity from rabbit intestine and shown to be a monomer attached to the plasma membrane by a GPI anchor (Galand 1984; Ruf et al. 1990). A human cDNA encoding a closely homologous protein has been cloned and its protein product has been shown to have trehalase activity in vitro (Ishihara et al. 1997). The human enzyme has not been characterized further, and so both the posttranslational modifications of the human enzyme and its activity in vivo have been inferred from the properties of the well studied rabbit enzyme.
Trehalase deficiency has been described in two isolated cases in Europe (Bergoz 1971; Madzarovovà-Nohejlova 1973) and at high frequency in a population of Greenland natives (Gudmand-Hoyer et al. 1988) but molecular defects responsible for the deficiency have not yet been described so it is not annotated in Reactome.