CEACAMs are intercellular adhesion molecules that form Ca ²⁺-dependent homo- and heterotypic interactions, and typically serve as pathogen receptors. All CEACAMs are heavily glycosylated and contain one N-terminal V-type Ig-like domain. CEACAMs also exhibit variability in their structure by containing transmembrane domains (#CEACAM-1, 3 & 4), GPI-linked domains (#5, 6, 7, & 8), or CD66 designations (#1, 3, 5, 6, & 7).