Binds to tRNA and functions as a cofactor for the methionyl-tRNA synthetase (MetRS) and glutamyl-tRNA synthetase (GluRS). Forms a complex with MetRS and GluRS and increases their affinity for cognate tRNAs due to the presence of a tRNA binding domain in its middle and C-terminal part. Binds specifically G4 quadruplex nucleic acid structures (these are four-stranded right-handed helices, stabilized by guanine base quartets). Also required for cytoplasmic confinement of the synthetases and tRNA. Component of a yeast aminoacyl-tRNA synthase (aaRS) complex formed by methionyl-tRNA synthase MES1, glutamyl-tRNA synthase GUS1 and the tRNA aminoacylation cofactor ARC1 in a stoichiometric complex. Interacts (via N-ter) with MES1 (via N-ter) and GUS1 (via N-ter). Can also form a stable binary complex with either MES1 or GUS1 that is functional in terms of aminoacylation. Largely excluded from the nucleus. Present with 57700 molecules/cell in log phase SD medium. Belongs to the tRNA-aminoacylation cofactor ARC1 family.