Ohe Yoshihide, Ohnishi Hiroshi, Okazawa Hideki, Tomizawa Kyoko, Kobayashi Hisae, Okawa Katsuya, Matozaki Takashi
Biosignal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-Machi, Maebashi, Gunma 371-8512, Japan.
Biochem Biophys Res Commun. 2003 Sep 5;308(4):719-25. doi: 10.1016/s0006-291x(03)01454-2.
Membrane glycoproteins of neural cells play crucial roles in axon guidance, synaptogenesis, and neuronal transmission. We have here characterized membrane glycoproteins containing terminal alpha-mannose residues in rat brain membranes. Affinity purification using Galanthus nivalis agglutinin, that is highly specific for terminal alpha-mannose residues, revealed a 50-kDa protein as well as 80-kDa SHPS-1 and 45-kDa beta2 subunit of Na,K-ATPase in rat brain membranes. Combination of N-terminal peptide sequencing and mass spectrometry indicated that the 50-kDa protein was rat nucleotide pyrophosphatase-5 (NPP-5). In contrast to other NPPs, NPP-5 was a type-I transmembrane protein. Northern blot analysis showed that NPP-5 was highly expressed in brain, but also expressed in other peripheral tissues. However, we could not detect either the NPP activity or the lysophospholipase D activity in the immunoprecipitates with antibodies to NPP-5 from rat brain membranes. These data, therefore, suggest that NPP-5 is a neural oligomannosidic glycoprotein that may participate in neural cell communications.
神经细胞膜糖蛋白在轴突导向、突触形成和神经元传递中发挥着关键作用。我们在此对大鼠脑膜中含有末端α-甘露糖残基的膜糖蛋白进行了表征。使用对末端α-甘露糖残基具有高度特异性的雪花莲凝集素进行亲和纯化，结果显示大鼠脑膜中存在一种50 kDa的蛋白质以及80 kDa的SHPS-1和45 kDa的Na,K-ATP酶β2亚基。N端肽测序和质谱分析相结合表明，该50 kDa的蛋白质是大鼠核苷酸焦磷酸酶-5（NPP-5）。与其他NPP不同，NPP-5是一种I型跨膜蛋白。Northern印迹分析表明，NPP-5在脑中高度表达，但在其他外周组织中也有表达。然而，我们在来自大鼠脑膜的用NPP-5抗体进行免疫沉淀的沉淀物中未检测到NPP活性或溶血磷脂酶D活性。因此，这些数据表明NPP-5是一种神经寡甘露糖苷糖蛋白，可能参与神经细胞通讯。
