Figure 4.

Cells expressing active GNE produced more sialylated glycans and fewer tetra-antennary N-linked glycans. Cells were cultured for 24 h, and membrane proteins were isolated. Permethylated N-linked glycans from K88, K20, +GNE, +D176V, and +Kinase cells were analyzed by MALDI-TOF and MALDI-TOF/TOF. Derived structural assignments, based on composition, tandem MS, and biosynthetic knowledge and relative abundances were used to assess complex N-glycan levels of sialylation (A), numbers of antennae (B), and tetra-antennary and extended LacNAc (C). A full list of structural compositions is available in supplemental Fig. 1 and Table 1. Mass spectrometry data are based on analysis of a single set of samples.