Fig. 4: EGF-like repeat in the NECD domain and its modifications.
From: Structure, function, and pathology of protein O-glucosyltransferases
Multiple EGF-like repeats present in the NECD harbor consensus sequences having a target site for glycosyltransferases. POGLUT1 adds O-Glc to a Ser residue in the consensus sequence C1-X-S-X-P/A-C2, which can further be extended to Xyl-Xyl-Glc-O trisaccharide by GXYLT1/2 and XXYLT1. The serine between C1 and C2 is highly conserved relative to other glycosylated sites, where both Ser and Thr can be found, and its the conformation of C1–C2 motif because of which POGLUTs can not glucosylate the Thr residue. POGLUT2 and 3 glucosylate a Ser residue conserved in C3–C4 of the EGF-like repeats and its further extension is not yet reported. POFUT1 adds O-Fuc to Ser/Thr residues between C2 and C3 of EGF repeats, which can further be elongated by Fringe enzyme. Moreover, the Ser/Thr residues between C5 and C6 is O-GlcNAcylated by a EOGT in Drosophila and mammals.
