The exchange of macromolecules between cytoplasm and nucleus is mediated at nuclear pore complex (NPC) which is very large structure (~120 MDa in vertebrates) that spans inner and outer nuclear membranes. In vertebrates, it is composed of approximately 30 different nucleoporins (Nups) and it is estimated that NPC contains ~ 600 individual proteins constructing a structure of ~125 x ~150 nm.
Nucleporins can be classified into three groups:
i) transmembrane Nups, docking the nuclear pore complex into nuclear envelope,
ii) FG-Nups, forming the basis of permeability barrier of the NPC that they contain characteristic FG( phenylalanine-glycine) repeats,
iii) structural Nups, acting as a scaffold between transmembrane and FG-Nups.
Particularly, FG-nucleoporins are able to make transient interaction with soluble transport receptors of the importin β superfamily. They form transport complex with cargoes by recognizing nuclear localization signals (NLSs) and nuclear export signals (NESs) in import and export cargoes, respectively. In addition to general function of FG-nucleoporins in forming selective permeability barrier of the nuclear pore complex, particular FG-nucleoporins have distinct roles in specific nuclear transport pathways. In a collaboration with Ralph Kehlenbach’s group at the UMG, we are trying to identify roles of FG-nucleoporins in particular nuclear transport pathways by using state-of-art proteomic approaches.