The invention generally relates to a bone growth factor, and more particularly to compositions including NELL1, articles of manufacture including NELL1 and methods of using NELL1 to induce bone formation. This invention also provides methods for the expression and purification of NELL1 and NELL2 peptides.
1. A polypeptide comprising a NELL1 peptide and a secretory signal peptide:
wherein the secretory signal peptide is selected from the group consisting of a melittin signal sequence, a drosphila immunoglobulin-binding protein signal sequence, an equine interferon-gamma (eIFN-gamma) signal peptide, a snake phospholipase A2 inhibitor signal peptide, a human lysozyme signal peptide, and a chicken lyzozyme signal peptide.
2. The polypeptide of claim 1 , wherein the NELL1 peptide is selected from the group comprising: SEQ ID NO:2, SEQ ID NO:4, or SEQ ID NO:6.