Analysis of galectin 1-mediated cell signaling by combined precipitation and electrophoresis techniques

Galectin-1 (GAL1) is a beta-galactoside-binding protein that has been impli cated in the regulation of viability of lymphoid cells. However, the signal ing pathway governed by the binding of GAL1 to the cell membrane is not und erstood yet. As a first step toward the elucidation of GAL1-initiated signa ling events, electrophoresis techniques such as sodium dodecyl sulfate-poly acrylamide gel electrophoresis (SDS-PAGE), and two-dimensional electrophore sis (2-DE) were used together with precipitation techniques. This allowed u s to identify the membrane receptor of GAL1, and to characterize the signal resulting from the binding of GAL1 to this receptor. Our results demonstra te that the tyrosine phosphatase CD45 is the receptor for GAL1, and that th e src-type tyrosine kinase Lyn is a target for the effects of GAL1/CD45 int eractions in B-cells. Furthermore, these results show the usefulness of com bined precipitation and electrophoresis techniques to analyze phosphotyrosi ne-dependent mechanisms during the study of cell functions.