Investigation of Galectin-3 Function in the Reproductive Tract by Identification of Binding Ligands in Human Seminal Plasma
Galectin-3 is a β-galactoside binding protein with immunomodulatory properties and exerts its extracellular functions via interactions with glycoconjugate ligands. Therefore, to elucidate the function of galectin-3, binding ligands in human seminal plasma were investigated.
Method of study
Galectin-3 binding proteins were isolated from seminal plasma by affinity chromatography, and candidate ligands were identified by MS/MS. Biochemical methods were used to characterize the ability of galectin-3 to bind its ligands.
Identified galectin-3 ligands included CD13, MUC6, PAP, PSA, and ZAG. 1D and 2D electrophoretic analysis of seminal plasma demonstrated that CD13, PAP, PSA, and ZAG immunoreactivity co-migrated with galectin-3-reactive protein bands and spots at expected molecular weights and pIs. Inhibition assays indicated that CD13, PSA, PAP, and ZAG interact with galectin-3 in a protein–carbohydrate manner.
The galectin-3 binding ligands identified in this study indicate multiple roles for galectin-3 in the reproductive and immunological functions of seminal plasma.