Liat1, short for Ligand of Ate1, is a protein initially discovered through its interaction with arginyl-tRNA protein transferase 1 (Ate1), a component of the Arg/N-degron pathway of protein degradation. It stimulates the in vitro N-terminal arginylation of a model substrate by Ate1 and has a higher affinity for certain Ate1 isoforms [1]. Vertebrate and some invertebrate genomes encode Liat1-like proteins. In primates, Liat1 genes are subtelomeric, and Liat1 proteins in some primates have tandem repeats of a 10-residue sequence, which may contribute to primate evolution [1].

Mouse Liat1's N-terminal half has an intrinsically disordered region (IDR) facilitating liquid-liquid phase separation (LLPS) in the nucleolus. A poly-K region within this IDR targets Liat1 to the nucleolus, and Jmjd6 modifies Liat1, inhibiting its nucleolar targeting [2]. Also, human tRNA^Arg can bind recombinant mouse LIAT1, suggesting LIAT1 is an RNA-binding protein, which may be related to TDP-43 proteostasis and associated diseases [3].

In conclusion, Liat1 is involved in protein degradation pathways via its interaction with Ate1, participates in nucleolar LLPS, and has the potential to bind RNA. Studies on Liat1, especially those using mouse models, contribute to understanding its role in protein and RNA metabolism, as well as its possible implications in neurodegenerative and myodegenerative diseases related to TDP-43 malfunctions [1,2,3].