STRUCTURE AND BIOLOGICAL FUNCTIONS OF GALECTIN-3. PART I

Galectin-3 is a member of a family of beta-galactoside-binding animal lectins and is the only chimera type galectin. Galectin-3 consists of two structural domains: a N-terminal domain that contains a phosphorylation site and a repeated 9 amino acids sequence rich in Pro, Gly, Tyr and Glu; and a C-terminal domain that contains a carbohydrate recognition domain. In human genome galectin-3 is coded by a single gene LGALS3 which is situated on chromosome 14 and composed of six exons and five introns. Galectin-3 is localized in the cytoplasm as well as in the nucleus. Galectin-3 is involved in many biological processes, such as: cell-cell and cell-extracellular matrix adhesion, mRNA splicing, cell growth and differentiation, cell cycle, signaling, apoptosis and angiogenesis. Consequently, galectin-3 is involved in regulation immune reaction, tumor growth and metastasis. Despite of fact that galectin-3 is synthesised by free ribosomes in the cytosol and lacks signal sequence, there are evidence for its extracellular localization. Differential galectin-3 distribution is associated with many functions it performs in the cell.