This domain is found in Actinobacillus pleuropneumoniae HMW1C (ApHMW1C). HMW1 adhesin is an N-linked glycoprotein that mediates adherence to respiratory epithelium through N-glycosylation of protein acceptor sites and O-glycosylation of sugar acceptor sites. This domain forms an all alpha domain (AAD) when combined with the N-terminal domain. The AAD interacts extensively with the C-terminal GT-B fold in order to create a unique groove with the potential to accommodate the acceptor protein [1].

1: Structural insights into the glycosyltransferase activity of the Actinobacillus pleuropneumoniae HMW1C-like protein. Kawai F, Grass S, Kim Y, Choi KJ, St Geme JW 3rd, Yeo HJ; J Biol Chem. 2011;286:38546-38557. PMID:21908603