Recombinant human CYR61 is a 39.5 kDa protein containing 357 amino acid residues. It is composed of four distinct structural domains (modules); the IGF binding protein (IGFBP) domain, the von Willebrand Factor C (VWFC) domain, the Thrombospondin type-I (TSP type-1) domain, and a C-terminal cysteine knot-like domain (CTCK).