Drosophila egghead encodes a beta 1,4-mannosyltransferase predicted to form the immediate precursor glycosphingolipid substrate for brainiac.
Wandall HH, Pedersen JW, Park C, Levery SB, Pizette S, Cohen SM, Schwientek T, Clausen H. J Biol Chem. 2003 Jan 17; 278(3):1411-4. Epub 2002 Nov 25.