May interact with other CEACAM proteins on the sperm surface. Abundant in seminal vesicle and traces in epididymis and prostate (at protein level). Highly expressed in seminal vesicle, minor in colon and placenta and, to a lesser extent, in small intestine, caecum, stomach, salivary gland and bone marrow. Present in trace amounts on 5.5 dpc, increased remarkably from 6.5 dpc to a maximum on 9.5 dpc and rapidly declined thereafter to an almost undetectable level until delivery. First appeared at a considerable level in 3-week-old mice. Thereafter, the amount of transcript began increasing rapidly at 4-week-old mice and reached a maximum in 7-week-old mice. Belongs to the immunoglobulin superfamily. CEA family.