This gene encodes a member of the alpha2-macroglobulin/complement superfamily. The encoded GPI-linked glycoprotein is found on the cell surface of platelets, activated T-cells, and endothelial cells. The protein binds to and negatively regulates signaling of transforming growth factor beta (TGF-beta). Multiple transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, Apr 2009]