O-GlcNAc-ylation in the Nuclear Pore Complex.

O-GlcNAc-ylation is the post-translational addition of an O-linked β-N-acetylglucosamine to the serine and threonine residues of thousands of proteins in eukaryotic cells. Specifically, half of the thirty different types of protein components in the nuclear pore complex (NPC) are modified by O-GlcNAc, of which the majority are intrinsically disordered nucleoporins (Nups) containing multiple phenylalanine-glycine (FG) repeats. Moreover, these FG-Nups form a strict selectivity barrier with a high density of O-GlcNAc in the NPC to mediate bidirectional trafficking between the cytoplasm and nucleus. However, the roles that O-GlcNAc plays in the structure and function of the NPC remain obscure. In this review paper, we will discuss the current knowledge of O-GlcNAc-ylated Nups, highlight some new techniques used to probe O-GlcNAc's roles in the nuclear pore, and finally propose a new model for the effect of O-GlcNAc on the NPC's permeability.