WDR4 (WD Repeat-Containing Protein 4), also known as TRM82, is a member of the WD repeat protein family. WD repeats are minimally conserved regions of approximately 40 amino acids typically bracketed by gly-his andtrp-asp (GH-WD), which may facilitate formation of heterotrimeric or multiprotein complexes. METTL1 (Methyltransferase-Like Protein 1), also known as TRM8, contains a conserved S-adenosylmethionine-binding motif and is inactivated by the protein kinase B (PKB) and ribosomal S6 kinase (RSK) under growth factor stimulation. WRD4 and METTL1 that form a complex are required for tRNA (guanine(46)-N(7))-methyltransferase activity. More than 90 different modified nucleosides have been identified in tRNA. Among the tRNA modifications, the 7-methylguanosine (m7G) modification is found widely in eubacteria, eukaryotes, and a few archaea. In most cases, the m7G modification occurs at position 46 in the variable region and is a product of tRNA (m7G46) methyltransferase. The m7G46 modification forms a tertiary base pair with C13-G22, and stabilizes the tRNA structure.
