The closely related structures of L-glycero-D-manno-heptose and D-mannose are highlighted for comparison. There is, however, no sequence similarity between the enzyme that attaches the innermost heptose in E. coli (WaaC) and the enzyme that attaches the mannose residue in R. leguminosarium (LpcC) (14, 19). Only the major molecular species are indicated, which, in the case of R. leguminosarum, is designated component D-1 (2, 8, 9, 12).