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Glycosyltransferase complexes improve glycolipid synthesis
Author(s) -
Spessott Waldo,
Crespo Pilar M.,
Daniotti José Luis,
Maccioni Hugo J.F.
Publication year - 2012
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/j.febslet.2012.05.041
Subject(s) - lactosylceramide , chemistry , sialic acid , biochemistry , enzyme
The synthesis of gangliosides GM3 and GD3 is carried out by the successive addition of sialic acid residues on lactosylceramide (LacCer) by the Golgi located sialyltransferases Sial‐T1 and Sial‐T2, respectively. CHO‐K1 cells lack Sial‐T2 and only express GM3. Here we show that the activity of Sial‐T1 was near 2.5‐fold higher in homogenates of CHO‐K1 cells transfected to express Sial‐T2 (CHO‐K1 Sial‐T2 ) than in untransfected cells. The appearance of Sial‐T1 enzyme or gene transcription activators or the stabilization of the Sial‐T1 protein were discarded as possible causes of the activation. Sial‐T2 lacking the catalytic domain failed to promote Sial‐T1 activation. Since Gal‐T1, Sial‐T1 and Sial‐T2 form a multienzyme complex, we propose that transformation of formed GM3 into GD3 and GT3 by Sial‐T2 in the complex leaves Sial‐T1 unoccupied, enabled for new rounds of LacCer utilization, which results in its apparent activation.