Wybutosine is a hypermodified guanosine found in phenylalanine tRNA. Wybutosine functions to stabilize codon-anticodon interactions during ribosome decoding and therefore supports the maintenance of the reading frame. In yeast, the homolog of this gene is essential for the synthesis of wybutosine. 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. [provided by RefSeq, Apr 2014].