This domain is found at the N-terminal of Erythromycin biosynthesis protein CIII (EryCIII) from Saccharopolyspora erythraea and similar proteins predominantly found in Actinobacteria and Enterobacterales. This protein is organised into two domains, both of them with a Rossmann-like alpha/beta fold. The N-terminal domain contains acceptor binding site [1].

1: Structure of the glycosyltransferase EryCIII in complex with its activating P450 homologue EryCII. Moncrieffe MC, Fernandez MJ, Spiteller D, Matsumura H, Gay NJ, Luisi BF, Leadlay PF; J Mol Biol. 2012;415:92-101. PMID:22056329