Selective expression of cell type specific cell-cell adhesion molecules in mouse hybrid cells.

Ca2+-dependent cell-cell adhesion systems (CDS) are present in a variety of cells which can be grouped into at least two qualitatively different types, the teratocarcinoma type (t-CDS) and the fibroblast type (f-CDS), where different classes of adhesion molecules operate, respectively. In order to study the regulatory mechanisms of expression of different CDS types, we made cell hybrids between teratocarcinoma OTF9 cells (t-CDS) and fibroblast L cells (f-CDS), and between OTF9 cells (t-CDS) and hepatoma MH cells (no CDS). We thus examined which type of CDS is expressed in hybrid clones using a probe, an antibody that recognizes t-CDS selectively. We isolated many hybrid clones with different phenotypes, all displaying CDS activity, and found that CDS functioning in each clone was either t-CDS or another type(s) of CDS. There were no clones in which both t-CDS and another type(s) of CDS are active. We therefore suggested that the expression or function of t-CDS and other types of CDS is mutually exclusive within a single cell.