Madore N, Smith K L, Graham C H, Jen A, Brady K, Hall S, Morris R
Molecular Neurobiology Group, New Hunt's House, EM Unit, GKT Medical and Dental School, Guy's Campus, London Bridge, London SE1 9RT, UK.
EMBO J. 1999 Dec 15;18(24):6917-26. doi: 10.1093/emboj/18.24.6917.
We have investigated the organization, on the plasma membrane and in detergent-insoluble membrane vesicles, of two neuronal glycosylphosphatidylinositol-anchored (GPI) proteins: Thy-1, a negative regulator of transmembrane signalling; and prion protein, whose rapid endocytosis and Cu(2+) binding suggest that it functions in metal ion uptake. Prion protein occurred on the neuronal surface at high density in domains, located primarily at the cell body, which were relatively soluble in detergent. Thy-1, although much more abundantly expressed on neurons, occurred at lower density over much of the surface of neurites (and in lower abundance at the cell body) in domains that were highly resistant to detergent solubilization. Detergent-insoluble membrane vesicles contained Thy-1 at a density similar to that on the neuronal surface. Vesicles containing each protein could be separated by immunoaffinity isolation; lectin binding showed that they were enriched in different glycoproteins. Our results demonstrate a structural diversity of the domains occupied by functionally different GPI proteins.
我们研究了两种神经元糖基磷脂酰肌醇锚定（GPI）蛋白在质膜和去污剂不溶性膜囊泡中的组织情况：Thy-1，一种跨膜信号传导的负调节因子；以及朊病毒蛋白，其快速内吞作用和铜（2+）结合表明它在金属离子摄取中发挥作用。朊病毒蛋白以高密度出现在神经元表面的特定区域，主要位于细胞体，这些区域相对易溶于去污剂。Thy-1虽然在神经元上表达量高得多，但在神经突大部分表面以较低密度出现（在细胞体中丰度较低），存在于对去污剂溶解具有高度抗性的区域。去污剂不溶性膜囊泡中Thy-1的密度与神经元表面相似。含有每种蛋白的囊泡可通过免疫亲和分离进行分离；凝集素结合表明它们富含不同的糖蛋白。我们的结果证明了功能不同的GPI蛋白所占据区域的结构多样性。
