FIG. 1.

Identification of putative SL metabolic genes in Giardia. A search of the Giardia genome database (30; www.giardiaDB.org) revealed the presence of only five putative genes for SL metabolism, which encode gSPT, gGlct-1 (GlcT-1 is also known as glucosylceramide synthase), and acid sphingomyelinases. It is not known if Giardia has the ability to carry out the reactions indicated by a multiplication sign because the BLASTP search did not reveal any significant matches of these genes with genes of other organisms. CoA, coenzyme A; GSLs, glycosphingolipids; SM, sphingomyelin.