Recently, a family of proteins structurally similar to the angiogenic regulating factors
angiopoietins was identified and designated “angiopoietin-like proteins”(Angptls). Encoded
by seven genes, Angptls 1 to 7 all possess an N-terminal coiled-coil domain and a C-
terminal fibrinogen-like domain, both characteristic of angiopoietins. However, Angptls do
not bind to either the angiopoietin receptor Tie2 or the related protein Tie1 and remain
orphan ligands. Nonetheless, Angptls 1, 2, 3, 4, and Angptl6/angiopoietin-related growth …