PLATELET-ENDOTHELIAL CELL-ADHESION MOLECULE-1 (PECAM-1 CD31) TYROSINEPHOSPHORYLATION STATE CHANGES DURING VASCULOGENESIS IN THE MURINE CONCEPTUS/

Vasculogenesis, the differentiation of mesodermal cells to angioblasts and the subsequent formation of blood islands and blood vessels by an gioblasts in the conceptus, is a dynamic process modulated, in part, b y cell-extracelluar matrix and cell-cell interactions in the presence of a variety of growth factors and morphogens. In this report we demon strate differential tyrosine phosphorylation of platelet-endothelial c ell adhesion molecule-1 (PECAM-1) during the formation of blood island s and vessels from clusters of extraembryonic and embryonic angioblast s in the murine conceptus. In addition, we identify the phosphorylatio n of a particular tyrosine residue in the PECAM-1 cytoplasmic domain, Tyr(686), which has the potential of mediating binding to Src homology 2 domain-containing proteins, affecting PECAM-1 cellular localization and endothelial cell migration.