The higher-order multimerized Ang ligands are difficult to handle experimentally as a consequence of their notoriously poor solubility. Consequently, several modified forms of the Ang proteins have been engineered to overcome these technical limitations. The first modified ANG1 molecule to be widely used was ANG1*, a chimeric molecule of ANG1 and ANG2 that includes the first 73 residues of human ANG2 fused to human ANG1,
starting at a residue 77