May act as an inhibitor of TGF-beta signaling. Interacts with TGFB1, TGFB2 and TGFB3. Expressed at highest levels in aorta, at intermediate levels in kidney and placenta and at lowest levels in brain, heart, liver, lung and skeletal muscle. Within the aorta, the strongest expression is found in the tunica media of the proximal ascending aorta, the descending thoracic aorta, the abdominal aorta and the coronary arteries. Within the kidney, expression is found in the interstitial cells. N-glycosylated. N-glycan heterogeneity at Asn-117: Hex5HexNAc4 (minor), dHex1Hex5HexNAc4 (major), Hex6HexNAc5 (minor) and dHex1Hex6HexNAc5 (minor).