Defective GM3 synthesis in Cog2 null mutant CHO cells associates to mislocalization of Lactosylceramide sialyltransferase in the Golgi complex.

WALDO SPESSOTT; ANDREA ULIANA; HUGO J. F. MACCIONI

NEUROCHEMICAL RESEARCH

SPRINGER/PLENUM PUBLISHERS

Año: 2010 vol. 35 p. 2161 - 2167

0364-3190

The conserved oligomeric Golgi (COG) complexis a eight subunit (COG1 to 8) tethering complexinvolved in the retrograde trafficking of multiple Golgiprocessing proteins. Here we studied the glycolipid synthesisstatus in ldlC cells, a Cog2 null mutant CHO cellline. Biochemical studies revealed a block in the couplingbetween LacCer and GM3 synthesis, resulting in decreasedlevels of GM3 in these cells. Uncoupling was not attributableto decreased activity of the glycosyltransferase thatuses LacCer as acceptor substrate (SialT1). Rather,immunocytochemical experiments evidenced a mislocalizationof SialT1 as consequence of the lack of Cog2 inthese cells. Co-immunoprecipitation experiments disclose aCog2 mediated interaction of SialT1 with the COG complexmember Cog1. Results indicate that cycling of someGolgi glycolipid glycosyltransferases depends on the participationof the COG complex and that deficienciesin COG complex subunits, by altering their traffic andlocalization, affect glycolipid composition.