Mac-2-binding glycoproteins. Putative ligands for a cytosolic beta-galactoside lectin.

Mac-2, a galactose-binding lectin secretion by activated macrophages, is the major non-integrin laminin-binding protein in these cells. Mac-2 is also expressed by epithelial cells in the intestine and kidney. We wished to identify intestinal glycoproteins other than laminin that have a high affinity for Mac-2 and that could be considered ...
as candidate ligands or partners for this lectin in intestinal epithelium. Certain lines of human colon adenocarcinoma cells produce two Mac-2-binding glycoproteins (M2BP-1 and M2BP-2) that were identified by their avid association with Mac-2 following detergent lysis and immunoprecipitation. These glycoproteins do not share a common epitope with Mac-2, and the interaction between Mac-2 and these proteins is mediated through the carbohydrate-binding domain of Mac-2 and sugar moieties on M2BP-1 and M2BP-2. M2BP-1 (98 kDa) and M2BP-2 (70 kDa) were purified by immunoaffinity chromatography and were specifically eluted with either galactose or lactose. Peptide maps revealed that M2BP-1 and M2BP-2 are structurally related. M2BP-1 is secreted and could conceivably associate with Mac-2 extracellularly. N-terminal sequence analysis of M2BP-2 suggests that these glycoproteins represent a unique subset of candidate ligands for this mammalian beta-galactoside lectin.
Mesh Terms:
Adenocarcinoma, Amino Acid Sequence, Antigens, Differentiation, Blotting, Western, Colon, Epithelial Cells, Epithelium, Galactosides, Galectin 3, Glycoproteins, Humans, Lectins, Ligands, Macrophages, Molecular Sequence Data, Precipitin Tests, Tumor Cells, Cultured
J. Biol. Chem.
Date: Oct. 05, 1991
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