THE RAT-LIVER ECTO-ATPASE C-CAM CDNA DETECTS INDUCTION OF CARCINOEMBRYONIC ANTIGEN BUT NOT THE MERCURIAL-INSENSITIVE ECTO-ATPASE IN HUMAN HEPATOMA LI-7A CELLS TREATED BY EPIDERMAL GROWTH-FACTOR AND CHOLERA-TOXIN

The rat liver ectoATPase has reportedly been cloned. The cDNA, a member of the carcinomebryonic antigen (CEA) gene family, was shown to increase aggregation of transfected cells, but ATPase activity was not evaluated. Using this cDNA as a probe to clone the mercurial-insensitive ectoATPase (MI-ectoATPase) of human hepatoma Li-7A cells, the cDNA obtained was that of CEA which has no ATPase activity. The probe also did not detect increased transcription when MI-ectoATPase activity was induced in Li-7A cells. It is concluded that the ''rat liver ectoATPase cDNA'' codes for a cell adhesion molecule but does not code for an ectoATPase. It was also discovered that expression of four CEA transcripts in Li-7A cells was markedly stimulated by a single growth modulator, EGF, and was further stimulated by acAMP elevating agent, cholera toxin. (C) 1995 Academic Press, Inc.