Iglesias M M, Rabinovich G A, Ambrosio A L, Castagna L F, Sotomayor C E, Wolfenstein-Todel C
Instituto de Química y Fisicoquímica Biológicas (UBA-CONICET), Facultad de Farmacia y Bioquímica, Junín 956, 1113 Buenos Aires, Argentina.
Glycobiology. 1998 Jan;8(1):59-65. doi: 10.1093/glycob/8.1.59.
Galectins, beta-galactoside-binding lectins, are extensively distributed in the animal kingdom and share some basic molecular properties. Galectin-3, a member of this family, is generally associated with differentiation, morphogenesis, and metastasis. In this study, galectin-3 was isolated from ovine placental cotyledons round the middle of the gestation period by lactose extraction followed by affinity chromatography on lactosyl-agarose, and separated from galectin-1 by size exclusion chromatography on a Superose 12 column. Under native conditions this lectin behaved as a monomer with an apparent molecular weight of approximately 29,000 and an isoelectric point of 9.0. The partial amino acid sequence of the peptides obtained by tryptic digestion of this protein followed by HPLC separation showed striking homology with other members of the galectin-3 subfamily. Furthermore, ovine placental galectin-3 exhibited specific mitogenic activity toward rat spleen mononuclear cells. Besides, this protein strongly reacted with a rabbit antiserum raised against a chicken galectin. Results obtained by Western blot analysis showed that its expression was greatly decreased in term placenta with respect to the middle of the gestation period, suggesting a regulated expression throughout development.
半乳糖凝集素，即β-半乳糖苷结合凝集素，广泛分布于动物界并具有一些基本的分子特性。该家族成员之一的半乳糖凝集素-3通常与分化、形态发生和转移相关。在本研究中，通过乳糖提取法，随后在乳糖基琼脂糖上进行亲和层析，从妊娠期中期的绵羊胎盘子叶中分离出半乳糖凝集素-3，并通过在Superose 12柱上进行尺寸排阻色谱法与半乳糖凝集素-1分离。在天然条件下，这种凝集素表现为单体，表观分子量约为29,000，等电点为9.0。通过对该蛋白进行胰蛋白酶消化，随后进行HPLC分离得到的肽段的部分氨基酸序列与半乳糖凝集素-3亚家族的其他成员具有显著的同源性。此外，绵羊胎盘半乳糖凝集素-3对大鼠脾脏单核细胞表现出特定的促有丝分裂活性。此外，该蛋白与针对鸡半乳糖凝集素产生的兔抗血清强烈反应。蛋白质印迹分析结果表明，与妊娠期中期相比，足月胎盘期其表达显著降低，提示其在整个发育过程中表达受到调控。
