Figure 3. Regulation of ganglioside biosynthesis pathways by N-glycan-dependent glycosyltransferase distribution and complex formation.
Inhibition of trimming by glucosidase I and II increases proteolytic turnover of GD3 synthase and prevents enzyme complex formation with GM2/GD2 synthase in the Golgi, suggesting that N-glycoprotein processing of glycosyltransferases is critical for ganglioside metabolism. The GD3 synthase-GM2/GD2 synthase complex is hypothesized to promote b-series complex ganglioside biosynthesis. Moreover, our group has proposed that binding of GD3 synthase to GM3 may facilitate enzyme complex formation (“lipid co-chaperone” hypothesis).