The DDX21 was first isolated as a nucleolar
protein that was recognized by an autoantibody [10]. DDX21 was
then identified as an interacting partner for the transcription factor
c-Jun and its helicase activity was involved in relocalization of
DDX21 from the nucleolus to the nucleoplasm [8]. It is reported that
DDX21 interacted with the 50 UTR of borna disease virus (BDV)
mRNA and controlled its translation [11].