The glycine arginine‐rich domain of the RNA‐binding protein nucleolin regulates its subcellular localization

Nucleolin is a multifunctional RNA Binding Protein (RBP) with diverse subcellular localizations, including the nucleolus in all eukaryotic cells, the plasma membrane in tumor cells, and the axon in neurons. Here we show that the glycine arginine rich (GAR) domain of nucleolin drives subcellular localization via protein‐protein interactions with a kinesin light chain. In addition, GAR sequences mediate plasma membrane interactions of nucleolin. Both these modalities are in addition to the already reported involvement of the GAR domain in liquid‐liquid phase separation in the nucleolus. Nucleolin transport to axons requires the GAR domain, and heterozygous GAR deletion mice reveal reduced axonal localization of nucleolin cargo mRNAs and enhanced sensory neuron growth. Thus, the GAR domain governs axonal transport of a growth controlling RNA‐RBP complex in neurons, and is a versatile localization determinant for different subcellular compartments. Localization determination by GAR domains may explain why GAR mutants in diverse RBPs are associated with neurodegenerative disease. Synopsis Nucleolin is a multifunctional RNA Binding Protein with diverse subcellular localizations. Here we show that the glycine arginine rich (GAR) domain drives localization of nucleolin via direct interaction with a kinesin light chain and plasma membrane association of arginine rich sequences. Nucleolin GAR domain binds a kinesin light chain, directly linking nucleolin‐mRNA complexes to kinesin motors for axonal transport. Heterozygous nucleolin GAR deletion neurons reveal deficits in axonal localization of nucleolin cargo mRNAs. Heterozygous nucleolin GAR deletion neurons reveal increased axonal outgrowth. The GAR domain is also required for membrane targeting of nucleolin. Graphical Abstract The glycine arginine rich (GAR) domain of nucleolin controls subcellular localization in axons by directly binding the kinesin motor.