Component of the elongator complex which is required for multiple tRNA modifications, including mcm5U (5-methoxycarbonylmethyl uridine), mcm5s2U (5-methoxycarbonylmethyl-2-thiouridine), and ncm5U (5-carbamoylmethyl uridine). The elongator complex catalyzes the formation of carboxymethyluridine in the wobble base at position 34 in tRNAs. tRNA modification; 5-methoxycarbonylmethyl-2-thiouridine-tRNA biosynthesis. Component of the elongator complex which consists of ELP1, ELP2, ELP3, ELP4, ELP5 and ELP6. Belongs to the ELP4 family. The elongator complex was originally thought to play a role in transcription elongation. However, it is no longer thought to play a direct role in this process and its primary function is thought to be in tRNA modification.