galectin1

Galectin-1, also known as Gal-1, is a member of the galectin family of beta-galactoside-binding lectins and is encoded by the LGALS1 gene in humans. It is a small soluble protein, with each monomer weighing about 14 kilodaltons, that readily forms noncovalent homodimers. The monomer contains a single carbohydrate recognition domain, enabling binding to beta-galactoside-containing glycans on the surfaces of cells and in the extracellular matrix.

Biochemical properties and localization: Gal-1 lacks a classical signal peptide and is primarily cytosolic, yet it can be secreted by a nonclassical pathway. Extracellular Gal-1 engages glycoconjugates on various cells, influencing adhesion, migration, and signaling. It also interacts with matrix proteins such as laminin and fibronectin, contributing to cell–matrix interactions.

Functions: Gal-1 participates in cell–cell and cell–matrix communication and modulates immune responses. It can induce apoptosis of activated T cells by cross-linking cell-surface glycoproteins, contributing to immune tolerance. It also affects macrophage polarization and inflammatory signaling, and can promote angiogenesis under certain conditions. In cancer, Gal-1 is variably associated with tumor progression and immune evasion, while in other contexts it can exert anti-inflammatory effects.

Clinical and research significance: Gal-1 is studied as a potential biomarker and therapeutic target in oncology and inflammatory diseases. Inhibitors and recombinant forms are explored to modulate immune responses, angiogenesis, and fibrosis. The effects of Gal-1 are highly context-dependent, reflecting differences among tissues and disease states.