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Dependence of rat liver CMP‐ N ‐acetylneuraminate:GM 1 sialyltransferase (SAT IV) activity on the ceramide composition of GM 1 ganglioside
Author(s) -
Pitto Marina,
Palestini Paola,
Masserini Massimo
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00262-1
Subject(s) - ceramide , sialyltransferase , chemistry , biochemistry , ganglioside , glycosphingolipid , glycosyltransferase , composition (language) , vesicle , sialic acid , enzyme , sphingolipid , substrate (aquarium) , phospholipid , stereochemistry , biology , membrane , apoptosis , ecology , linguistics , philosophy
The dependence of CMP‐ N ‐acetylneuraminate:GM 1 sialyltransferase (SAT IV) activity of rat liver Golgi apparatus on GM 1 ganglioside ceramide composition was evaluated. SAT IV activity was assayed on GM 1 molecular species carrying homogeneous ceramide moieties containing long chain bases of different length (18 or 20 C atoms) unsaturated or not, linked to 14:0, 16:0, 18:0 or 22:0 fatty acids. The results obtained in the presence of the detergent Triton CF‐54, when enzyme and substrate are presumably part of the same supramolecular structure, show that either the long chain base or the fatty acid composition can affect enzyme activity. This feature was not displayed when GM 1 was embedded in dipalmitoylphosphatidylcholine vesicles in the absence of detergent. Under the latter conditions, the enzyme was not sensitive to the lipid composition of GM 1 but to the ganglioside/phospholipid ratio in the vesicles. These results indicate for the first time that SAT IV is affected by the lipid composition of the substrate and strengthen the hypothesis that glycosyltransferases may contribute to control the cellular glycosphingolipid ceramide pattern.