ApeC domain was first identified from two apextrin-like proteins (ALP) of the amphioxus Branchiostoma japonicum. Our functional studies show that amphioxus ALP1 and ALP2 are important anti-bacterial effectors, and that the apeC domain of the ALP1/2 mediates the bacterial recognition by binding to bacterial muramyl dipeptide (MDP). Further analysis shows that the apeC domain is present in various proteins from cnidarians, molluscs, arthropods, hemichordates, echinoderms and amphioxus. The apeC domain is also found to form different domain combinations with other domains (in press).

1: Two apextrin-like proteins mediate extracellular and intracellular bacterial recognition in amphioxus. Huang G, Huang S, Yan X, Yang P, Li J, Xu W, Zhang L, Wang R, Yu Y, Yuan S, Chen S, Luo G, Xu A; Proc Natl Acad Sci U S A. 2014 Sep 3. pii: 2014; [Epub ahead of print] PMID:25187559