Tissue Specific Expression of Alternatively Spliced Murine

ABSTRACT PECAM-1 (CD31) is a cell adhe-sion molecule that is highly expressed at the sites of endothelial cell-cell contact and at lower levels on the surface of platelets and leukocytes. It is a member of the immunoglobulin gene superfamily and undergoes alternative splicing to generate several isoforms that differ only in their cytoplas-mic domains. The tissue distribution of the expres-sion of different PECAM-1 isoforms has not been previously defined. We have examined PECAM-1 expression in various mouse tissues and endothe-lial cells. PECAM-1 mRNA was highly expressed in lung, heart, and kidney, and to a lower extent in brain and liver. Most endothelial cells in cul-ture expressed high levels of PECAM-1 mRNA