Figure 2.

BIAcore assay for evaluation of angiopoietin-3 and -4 binding to the Tie1 and Tie2 receptors. BIAcore binding assays of the indicated angiopoietins or chimeric angiopoietins (having the fibrinogen-like domains of angiopoietin-3 or -4; as noted, binding of chimeric angiopoietins is determined by the fibrinogen-like domain) to BIAcore chips coated with immobilized Tie1 or Tie2 receptors was assessed in the presence of competition with excess amounts of either an irrelevant soluble receptor (TrkB) or soluble Tie1 or Tie2 receptors (6). For all the angiopoietins, binding is noted only to the Tie2 surface and not the Tie1 surface; consistent with this observation, only soluble Tie2 receptors compete for binding to the surface.