Tyrosine Phosphorylation of a 34-kDa Protein Induced by Cross-Linking a Novel Glycosylphosphatidylinositol-Anchored Glycoprotein (GPI-80) on Human Neutrophils That May Regulate Their Adherence and Migration
We previously found a novel glycosylphosphatidylinositol (GPI)‐ anchored glycoprotein designated GPI‐80 that modulates complement receptor 3 integrin‐dependent adhesion and in vitro transendothelial migration of neutrophils. In this study, we show that antibody‐mediated cross‐linking of GPI‐80 led to rapid tyrosine phosphorylation mainly of a 34‐kDa protein (pp34). Chemical inhibitors, such as genistein, sodium orthovanadate, wortmannin, cytochalasin B, Ro 31‐8220, and 1,2‐bis(2‐aminophenoxy)ethane‐ N, N, N, N,‐tetraacetic acid inhibited this response, whereas pertussis toxin had no effect. These findings demonstrate that the tyrosine phosphorylation of pp34 by cross‐linking GPI‐80 in human neutrophils involves tyrosine kinases, tyrosine phosphatases, phosphatidylinositol 3‐kinase, cytoskeleton reorganization, protein kinase C, and cytoplasmic calcium, but not heterotrimeric G proteins.