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 (By similarity). Component of a yeast aminoacyl-tRNA synthase (aaRS) complex formed by methionyl-tRNA synthase, glutamyl-tRNA synthase and the tRNA aminoacylation cofactor arc1 in a stoichiometric complex. Interacts with rar1/mes1 and gus1 (By similarity). Belongs to the tRNA-aminoacylation cofactor ARC1 family.