 As of 2019, human queuine requirements are not well understood, and the prevalence of queuine deficiency in humans is unknown.Once salvaged, queuine replaces a guanine base in the anticodon of certain tRNAs, where it appears to play a role in ensuring rapid and accurate recognition of the corresponding mRNAs' codons.In the absence of queuosine modification, translation at Q-decoded codons slows down to the point that many proteins cannot fold properly.