Nature and the multiple functions of the 67-kD elastin-/laminin binding protein

Numerous cell types, including fibroblasts, vascular smooth muscle cells, chondroblasts, monocytes, neutrophils, and several tumor cells express the 67-kD galactolectin, homologous to the alternatively spliced variant of beta-galactosidase. The 67-kD protein resides on the cell surfaces and is capable of interacting with elastin, laminin and collagen type IV. This peripheral membrane protein binds its matrix ligands but only in the absence of galactosugars, whereas binding of galactosugar-containing moieties to its lectin site changes its molecular folding which causes discharge of the ligand and release of the receptor from the cell surface. This review will address the functional significance of the single receptor that interacts with multiple matrix proteins and can be shed from cell surfaces by galactosugars. I will emphasize the role of the 67-kD protein in divergent cellular processes, such as cell-matrix attachment, matrix assembly, cellular chemotaxis, and active migration through the vascular walls.