Salmonella ushB, which encodes a membrane-bound UDP-sugar hydrolase, has an Escherichia coli orthologue (ushB c ) which does not detectably produce this activity. In this report, we show that ushB c does not produce any detectable protein either, despite being transcribed normally. Remarkably, ushB c is shown to have 100% sequence identity with E. coli cdh, previously characterised as encoding an active CDP-diglyceride hydrolase, an apparent contradiction with implications regarding enzyme evolution. We suggest that a useful gene designation is cdh (ushB c ) rather than either ushB c or cdh, alone.