Elongator complex-associated factor that is not a structural subunit but rather transiently contacts the complex. Required for an early step in synthesis of 5-methoxycarbonylmethyl (mcm5) and 5-carbamoylmethyl (ncm5) groups present on uridines at the wobble position in tRNA (By similarity). Interacts with the elongator complex. Belongs to the KTI12 family.