Recombinant soluble human CD69 dimer produced in Escherichia coli: Reevaluation of saccharide binding

We reevaluate here an earlier report of monosaccharide binding by the C-typ e lectin-like, leukocyte surface protein CD69 in the form of a recombinant soluble dimer, and we examine polysaccharide binding by the protein. We hav e expressed in Escherichia coil a new construct of the extracellular part ( Q(65)-K-199) of human CD69. We describe the folding in vitro to produce, in good yield, the protein in a soluble, disulphide-linked, dimeric form, and the results of binding experiments with monosaccharides: glucose, galactos e, mannose, fucose, N-acetylglucosamine, and N-acetylgalactosamine, linked to bovine serum albumin. Monosaccharide-binding signals are not detectable. Among the polysaccharides, heparin, chondroitin sulphates A, B, and C, fuc oidan, and dextran sulphate, CD69 dimer gives a weak binding signal with fu coidan. (C) 1999 Academic Press.