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STUDIES ON THE BIOSYNTHESIS OF GLYCO‐SPHINGOLIPIDS IN CULTURED MOUSE NEUROBLASTOMA CELLS: CHARACTERIZATION AND ACCEPTOR SPECIFICITIES OF N‐ACETYLNEURAMINYL‐ AND N‐ACETYLGALACTOSAMINYLTRANSFERASES
Author(s) -
Kemp S. F.,
Stoolmiller A. C.
Publication year - 1976
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1976.tb10400.x
Subject(s) - lactosylceramide , biosynthesis , glycosyltransferase , biochemistry , sphingolipid , enzyme , biology , ganglioside , sialyltransferase , catabolism , cell culture , genetics
— The pathway of biosynthesis of N ‐acetylgalactosamine‐containing gangliosides in mouse neuroblastoma has been studied using NB41A cells grown in monolayer tissue culture. Cell‐free enzyme preparations catalyzed the transfer of NeuNAc from CMP‐NeuNAc to lactosylceramide (GL‐2a), to form G M3 . Asialo‐G M2 was neither an acceptor nor a competitive inhibitor of the sialyltransferase (CMP‐NeuNAc: GL‐2a N‐acetylneuraminyltransferase, EC 2.4.99.‐) under a variety of experimental conditions. Enzyme preparations also contained an N ‐acetylgalactosaminyltransferase (UDP‐GalNAc. G M3 N ‐acetylgalactosaminyltransferase, EC 2.4.1.‐) which catalyzed the conversion of G M3 to G M2 . No significant transfer of N ‐acetylgalactosamine to GL‐2a could be demonstrated. The results of the glycosyltransferase assays support the concept that the first NeuNAc of brain gangliosides is introduced into GL‐2a. The present data suggests that the occurrence of asialo‐G M2 in NB41A cells under some culture conditions is a consequence of the catabolism of higher gangliosides.