Lukyanov Pavel, Furtak Vyacheslav, Ochieng Josiah
Division of Cancer Biology, Department of Biomedical Sciences, Meharry Medical College, 1005 D.B. Todd Blvd., Nashville, TN 37208, USA.
Biochem Biophys Res Commun. 2005 Dec 16;338(2):1031-6. doi: 10.1016/j.bbrc.2005.10.033. Epub 2005 Oct 18.
The precise mechanism by which galectin-3 and other cytosolic proteins that lack signal peptides are secreted is yet to be elucidated. In the present analyses, we determined that galectin-3, a beta-galactoside binding protein, can interact directly with membrane lipids in solid phase binding assays. More interestingly, we determined by spectrophotometric methods that it can spontaneously penetrate the lipid bilayer of liposomes in either direction. These findings suggest that galectin-3 on its own has the capacity to traverse the lipid bilayer. Whereas the situation is rather simplified in liposomes, the interaction of galectin-3 with the plasma membrane may involve cholesterol-rich membrane domains where galectin-3 can be concentrated and form multimers or interact covalently with other proteins.
半乳糖凝集素-3和其他缺乏信号肽的胞质蛋白的精确分泌机制尚待阐明。在本分析中，我们确定，β-半乳糖苷结合蛋白半乳糖凝集素-3在固相结合试验中可直接与膜脂相互作用。更有趣的是，我们通过分光光度法确定，它可以自发地双向穿透脂质体的脂质双层。这些发现表明，半乳糖凝集素-3自身具有穿越脂质双层的能力。虽然在脂质体中情况较为简单，但半乳糖凝集素-3与质膜的相互作用可能涉及富含胆固醇的膜结构域，在这些结构域中半乳糖凝集素-3可以聚集并形成多聚体，或与其他蛋白质共价相互作用。
