Carbohydrate Binding Protein 35

Abstract

Carbohydrate Binding Protein 35(CBP35) is a galactose-specific lectin belonging to the L-30 subgroup of the S-type family of animal lectins. The polypeptide chain(M -35,000) consists of two distinct domains; a proline- and glycine-rich domain at the amino-terminal half and a carbohydrate recognition domain at the carboxyl-terminal half. The amino acid sequence information also indicates that CBP35 is identical to (within a given species) or homologous with (between species) proteins isolated and studied under odier names: (i)L-34, a tumor cell lectin; (ii)human and rat lung lectins, HL-29 and RL-29; (iii)IgE-binding protein, eBP; (iv)LBP, a non-integrin type laminin-binding protein; and (v)Mac-2, a cell surface marker of thioglycollate-elicited macrophages. It is curious that the same polypeptide, under different guises, is found in two topologically distinct compartments of a cell: intracellular(cytosol and nucleus) and extracellular(cell surface and medium). Studies of the possible function(s) of this protein have, in turn, been guided by this dual localization: as a cell surface receptor for carbohydrate-containing ligands, including laminin and IgE, and as a nucleocytoplasmic shuttle in the form of a ribonucleoprotein complex. © 1992, FCCA(Forum: Carbohydrates Coming of Age). All rights reserved.