Identification of protease-sensitive sites in Human Endothelial-Monocyte Activating Polypeptide II protein

The cleaved approximate to 22-kDa form of Endothelial-Monocyte Activating Polypeptide [mature (in) EMAP II] functions as a potent inhibitor of tumor growth. Although the anti-tumor effect of mEMAP II has been described, little is known regarding the cleavage of mEMAP II from its precursor form (pEMAP II). We determined that pEMAP II is expressed at the cell membrane surface and proteinases MMP-9, elastase, and cathepsin L release protein fragments consistent with mEMAP II molecular mass. MMP-9 and elastase generate a approximate to 25-26 kDa spanning fragments, while cathepsin L generates a approximate to 22 kDa fragment. Although several fragments are processed from pEMAP II within a 44 AA residue stretch, cathepsin L cleaves pEMAP II within 4 amino acids of the determined N-terminal sequence, suggesting that this region is sensitive to proteinases. (c) 2006 Elsevier Inc. All rights reserved.