CD146,also known as melanoma cell adhesion molecule (MCAM) or MUC18,originally identified as a biomarker of melanoma progression,is a transmembrane glycoprotein of 113-130 kDa,belonging to the immunoglobulin (Ig) superfamily. Structurally,it consists of five Ig domains,a transmembrane domain,and a cytoplasmic region. In normal adult tissue,CD146 is primarily expressed by vascular endothelium and smooth muscle. CD146 is a key cell adhesion protein in vascular endothelial cell activity and angiogenesis,and has been used as marker of circulating endothelium cells (CECs). In addition to the membrane-anchored form of CD146,a soluble form of CD146 (sCD146,105 kDa) has also been found in human plasma and in the supernatant of cultured human endothelial cells. This antibody detects a band at approximately 120 kDa that corresponds to the molecular weight of glycosylated CD146. Treatment of lysates of HepG2 cells and L02 cells with PNGase F,which removes oligosaccharides from N-linked glycoproteins,led to a down-shift of the detected band.
