This domain may have a role in cell adhesion. It is called the AMOP domain after Adhesion associated domain in MUC4 and Other Proteins. This domain is extracellular and contains a number of cysteines that probably form disulphide bridges [1].

1: AMOP, a protein module alternatively spliced in cancer cells. Ciccarelli FD, Doerks T, Bork P; Trends Biochem Sci 2002;27:113-115. PMID:11893501