Boucias D G, Pendland J C
Department of Entomology and Nematology, University of Florida, Gainesville 32611-0620.
Insect Biochem Mol Biol. 1993 Mar;23(2):233-42. doi: 10.1016/0965-1748(93)90004-c.
The Spodoptera exigua galactose binding lectin, extracted from hemolymph by affinity chromatography, was comprised of large molecular weight aggregates (100-700 kDa). SDS-PAGE of this lectin preparation revealed it to contain 2 subunits of 33.2 and 34.4 kDa in equimolar concentrations. These subunits had similar amino acid profiles, possessed identical N-terminal sequences and reacted equally to a bank of antilectin monoclonal antibodies. By staining Western blots with various lectin conjugate probes, we demonstrated that the 34.4 kDa subunit contains complex mannose residues, suggesting that this subunit is the glycosylated form of the 33.2 kDa subunit. The N-terminal sequence of the S. exigua lectin was distinct from other invertebrate galactose binding lectins. Light microscopy in combination with immunoelectron microscopy was used to localize the S. exigua lectin in the granules of the granulocyte class of hemocytes. Degranulation of these cells resulted in the release of the lectin. Isotope incorporation studies followed by immunoprecipitation with a S. exigua monoclonal antibody demonstrated that the fat body was the major site of lectin synthesis. Similar studies with hemocyte monolayers did not result in the production of detectable levels of 35S-labeled S. exigua lectin.
通过亲和层析从血淋巴中提取的甜菜夜蛾半乳糖结合凝集素由大分子量聚集体（100 - 700 kDa）组成。该凝集素制剂的SDS - PAGE显示其含有等摩尔浓度的33.2 kDa和34.4 kDa的2个亚基。这些亚基具有相似的氨基酸谱，拥有相同的N端序列，并且对一系列抗凝集素单克隆抗体有相同反应。通过用各种凝集素共轭探针染色蛋白质印迹，我们证明34.4 kDa亚基含有复杂的甘露糖残基，这表明该亚基是33.2 kDa亚基的糖基化形式。甜菜夜蛾凝集素的N端序列与其他无脊椎动物半乳糖结合凝集素不同。结合免疫电子显微镜的光学显微镜用于将甜菜夜蛾凝集素定位在血细胞粒细胞类别的颗粒中。这些细胞的脱粒导致凝集素的释放。同位素掺入研究随后用甜菜夜蛾单克隆抗体进行免疫沉淀表明脂肪体是凝集素合成的主要部位。用血细胞单层进行的类似研究未产生可检测水平的35S标记的甜菜夜蛾凝集素。
