title: Ecto-ganglioside-sialidase activity of herpes simplex virus-transformed hamster embryo fibroblasts.
abstract: Cellular location of ganglioside-sialidase activity was determined in confluent hamster embryo fibroblasts transformed with herpes simplex virus type 2. Approximately equal specific activities of ganglioside-sialidase activity were found to be associated with the crude lysosomal and crude plasma membrane fractions isolated from whole cell homogenates. Whole transformed cells hydrolyzed exogenous ganglioside substrate, suggesting a partial location of the cellular sialidase on the outer surface of the plasma membrane of these cells. Intact cells were treated with the diazonium salt of sulfanilic acid, a nonpenetrating reagent inhibitory to ecto-enzymes (DePierre, J.W., and M. L. Karnovsky. 1974. J. Biol. Chem. 249:7111-7120). Cytoplasmic lactate dehydrogenase activity was not inhibited by this treatment, and mitochondrial succinate dehydrogenase activity was inhibited only 10%, indicating that intracellular enzymes were not affected. 5'-Nucleotidase activity was diminished 90%, and sialidase very rapidly lost 40% of its exogenously directed activity. These results show that, in herpes simplex virus-transformed fibroblasts, ganglioside-sialidase is both a lysosomal and a plasma membrane enzyme. The plasma membrane sialidase is capable of acting on endogenous plasma membrane sialolipids and also functions in the cultured transformed cell as an ecto-enzyme which can attack exogenous substrates.
mesh_terms: D002458:Cell Fractionation; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology*; D002471:Cell Transformation, Neoplastic; D003979:Diazonium Compounds / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008247:Lysosomes / Q000201:enzymology*; D009439:Neuraminidase / Q000378:metabolism*; D018139:Simplexvirus; D013385:Succinate Dehydrogenase / Q000378:metabolism; D013425:Sulfanilic Acids / Q000494:pharmacology
chemical_list: D003979:Diazonium Compounds; D013425:Sulfanilic Acids; D007770:L-Lactate Dehydrogenase; D013385:Succinate Dehydrogenase; D009439:Neuraminidase