Sialic acid, galactose and fucose on the surface of Ehrlich ascites tumor cells grown in glucose-free medium in the presence of uridine.
1) The content and accessibility of terminal sialic acid and galactose residues as well as the incorporation of [3H]fucose into glycoconjugates were determined in 48-h cultures of Ehrlich ascites tumor cells in a glucose-free medium supplemented with uridine, a compound which can fulfil the necessary functions of glucose. 2) Sialic-acid residues accessible to sialidase cleavage were reduced from 695 +/- 80 nmol/10(9) cells (controls) to 284 +/- 22 nmol/10(9) cells (43% of controls). In situ labeling using periodate oxidation followed by sodium borotritiide reduction revealed a tritium incorporation of 47 +/- 11% that of controls (= 4.1 x 10(5) cpm/mg protein). 3) Labeling of galactose residues of 80-90% of that of controls was achieved after treatment of the cells with galactose oxidase/sodium borotritiide. A nearly six-fold enhancement of tritium incorporation into galactose of control cells was observed after sialidase/galactose oxidase treatment and sodium borotritiide reduction (1.5----8.8 x 10(5) cpm/mg protein); only a 3.6-fold increase (1.2 x 10(5)----4.3 x 10(5) cpm/mg protein) was found with glucose-free cultured cells. It is concluded that the galactose content of the cell surface is reduced to about 50% of controls. 4) The incorporation of tritium into acid-insoluble precipitate after 24 h incubation with [3H]fucose and the activity of the acid-soluble fraction were enhanced by about 85% as compared to controls. The pattern of inhibition by tunicamycin of [3H]fucose uptake and incorporation was the same in glucose-containing standard medium and in glucose-free uridine medium.(ABSTRACT TRUNCATED AT 250 WORDS)
Wenzel
A
A
Institut für Theoretische Medizin der Universität Marburg.
Schneider
F
F
D000818:Animals; D001894:Borohydrides; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism*; D002478:Cells, Cultured; D003470:Culture Media; D005260:Female; D005643:Fucose / Q000378:metabolism*; D005690:Galactose / Q000378:metabolism*; D005947:Glucose / Q000502:physiology; D051379:Mice; D010084:Oxidation-Reduction; D010504:Periodic Acid; D012794:Sialic Acids / Q000378:metabolism*; D014415:Tunicamycin / Q000494:pharmacology; D014529:Uridine / Q000494:pharmacology*
D001894:Borohydrides; D003470:Culture Media; D012794:Sialic Acids; D010504:Periodic Acid; D014415:Tunicamycin; D005643:Fucose; C025364:sodium borohydride; D005947:Glucose; D014529:Uridine; D005690:Galactose