<p>The <taxon tax_id="562">Escherichia coli</taxon> YbbB protein was shown to encode a selenophosphate-dependent tRNA 2-selenouridine synthase, essential for modification of some tRNAs to replace a sulphur atom with selenium [<cite idref="PUB00043071"/>]. This enzyme catalyses the transfer of selenium from selenophosphate for the conversion of 2-thiouridine to 2-selenouridine at the wobble position in tRNA. This enzyme works with SelD, the selenium donor protein, which also acts in selenocysteine incorporation. Although the members of this protein family show a fairly deep split, sequences from both sides of the split are supported by co-occurrence with, and often proximity to, the selD gene.</p> tRNA 2-selenouridine synthase