
<ArticleTitle>Abundant early expression of <prot>gpUL4</prot> from a human cytomegalovirus mutant lacking a repressive upstream open reading frame.</ArticleTitle>
<AbstractText>The human cytomegalovirus <prot>UL4</prot> gene encodes a 48-kDa glycoprotein, expression of which is repressed at the translational level by a short upstream open reading frame (<prot>uORF2</prot>) within the <prot>UL4</prot> transcript leader. Mutation of the <prot>uORF2</prot> initiation codon in the viral genome eliminates ribosomal stalling at the <prot>uORF2</prot> termination site, resulting in early and abundant <prot>gpUL4</prot> protein synthesis. This mutation does not appear to affect viral replication kinetics in human fibroblasts. These results reveal that the unusual <prot>uORF2</prot> inhibitory mechanism is a principal determinant of the abundance and timing of <prot>gpUL4</prot> expression but is nonessential for replication in cell culture.</AbstractText>
