AUTOTAXIN IS AN N-LINKED GLYCOPROTEIN BUT THE SUGAR MOIETIES ARE NOT NEEDED FOR ITS STIMULATION OF CELLULAR MOTILITY

Autotaxin is a 125kD autocrine motility factor that stimulates both ra ndom and directed motility in producing the human A2058 melanoma cell line. The recently cloned autotaxin has been demonstrated to bind stro ngly and specifically to concanavalin A (con A). In this study, we sho w that the oligosaccharide side chains on autotaxin are exclusively as paragine linked, since N-glycosidase F, but not neuraminidase or O-gly cosidase, decreases the protein molecular mass to 100-105kD. which is the calculated molecular mass of the deduced autotaxin polypeptide. Fu rthermore, removal of oligosaccharide side chains by N-glycosidase F c an be performed under mild conditions that retain motility-stimulating activity, suggesting that the oligosaccharide side chains are not nec essary for autotaxin to activate its receptor. Finally, when melanoma cells are treated with inhibitors of carbohydrate processing, such as N-methyl-1-deoxy-nojirimycin, 1-deoxymannojirimycin and swainsonine, t hey still secrete a motility-stimulating autotaxin. Therefore, the car bohydrate side chains on autotaxin are not necessary to stimulate moti lity; however, they may still play a role in folding, secretion or mai ntenance of the active conformation of the protein.