Both Aah (autotransporter adhesin heptosyltransferase) and TibC (tib is enterotoxigenic invasion locus B) are protein O-heptosyltransferases that act on multiple sites from repeat regions of proteins exported by autotransporters. Aah glycosylates AIDA, or autotransporter adhesin involved in diffuse adherence, TibC acts on TibA, but TibC can replace Aah. [Protein fate, Protein modification and repair]