Wybutosine (yW) is a hypermodified guanosine found in phenylalanine tRNA adjacent to the anticodon that stabilizes codon-anticodon interactions in the ribosome. In yeast, the homolog of this gene is essential for the synthesis of wybutosine (yW). The human genome contains two closely related genes that putatively function in wybutosine synthesis. The open reading frame of this locus is disrupted in some individuals. Thus, this locus appears to be an evolving pseudogene, but may still be functional in some members of the population. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Mar 2009]