Human Galectin-3BP/MAC-2BP Alexa Fluor® 532-conjugated Antibody

Galectin-3 binding protein (Galectin-3BP), also known as MAC-2 binding protein (MAC-2BP or M2BP), and the 90 kDa tumor associated antigen (TAA90K or 90K), is a secreted glycoprotein of the scavenger receptor cysteine-rich (SRCR) superfamily (1, 2). Galectin-3BP binds Galectin-3 (formerly MAC-2) with high affinity, but also binds Galectins -1 and -7, several collagen types, fibronectin, beta1 integrins and nidogen (3, 6, 7). It is widely expressed in all extracellular fluids and in pericellular areas of cell-rich tissues (1-3). The 585 amino acid (aa) human Galectin-3BP contains an 18 aa signal sequence and four definitive domains (4-6). Domain 1 is a group A scavenger receptor domain (4), domain 2 is a BTB/POZ domain that strongly mediates dimerization (5), and domain 3 is an IVR domain, that is also found following the POZ domain in Drosophila kelch protein. Although little is known about domain 4, recombinant domains 3 and 4 reproduce the solid-phase adhesion profile of full-length Galectin-3BP (5, 6). Glycosylation at seven N-linked sites, generates a molecular size of 85-97 kDa (1, 2, 6). Galectin-3BP dimers form linear and ring-shaped oligomers, most commonly decamers and dodecamers (3, 5). In vitro, Galectin-3BP has been shown to stimulate natural killer cells and lymphokine-activated killer cell activity (2). High Galectin-3BP expression has been correlated with tumor aggressiveness in several, but not all, study systems (7). Mature human Galectin-3BP shares 69% aa identity with mouse cyclophilin C-associated protein (CyCAP), which does not appear to bind Galectin-3 (8). Human Galectin-3BP also shares 73%, 67% and 68% aa identity with relatively uncharacterized orthologs in dog, rat and cow, respectively. A human N-terminally truncated sequence that begins within the BTB/POZ domain (aa 196) has been reported.