Fig. 1.

O-Linked glycans found on EGF repeats in Drosophila and mammals. Rectangles represent EGF repeats. Each modification is shown with the corresponding enzyme that adds the sugar. CG11388 is the only protein encoded by the Drosophila genome which shows a high level of homology to mammalian XXYLT1. However, its enzymatic activity remains to be verified. Addition of galactose and sialic acid to GlcNAc-fucose-O-glycans has not been observed in flies. The consensus sequence for each glycan is listed below, although the sequence for O-GlcNAc is based on a small number of confirmed sites. O-Glycans are attached to the underlined amino acid(s) in each consensus sequence. Note that a single EGF repeat can possess all three modifications (Matsuura et al. 2008). C, cysteine (the superscript numbers show the position of cysteines in the EGF repeat); X, any amino acid other than cysteine; S, serine; T, threonine; P, proline; A, alanine; Fng, Fringe; MFNG, manic fringe; LFNG, lunatic fringe; RFNG, radical fringe. This figure is available in black and white in print and in color at Glycobiology online.