Coyne K E, Crisci A, Lublin D M
Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110.
J Biol Chem. 1993 Mar 25;268(9):6689-93.
Many membrane proteins are anchored to the cell surface through covalent attachment to a glycosyl-phosphatidylinositol (GPI) structure. The GPI anchor is added to proteins in the endoplasmic reticulum following recognition of a signal in the COOH terminus of the protein. We show that the GPI anchoring signal can be completely recreated by the synthetic polymer Ser3-Thr8-Leu14, but not Thr11-Leu14, inserted at the COOH terminus of a protein. This is consistent with previous reports that a small amino acid such as Ser, Gly, or Ala, but not Thr, is required at the GPI attachment site. Analysis of synthetic amino acid sequences established a basic three-part signal for GPI anchoring: a cleavage/attachment domain that requires small amino acids at the first (GPI anchor attachment) and third positions but with little specificity at the middle position, a spacer domain of approximately 8-12 amino acids, and a hydrophobic domain of at least 11 amino acids. The ability to design a totally synthetic GPI anchoring signal will allow precise probing of the fine structure of this signal.
许多膜蛋白通过与糖基磷脂酰肌醇（GPI）结构共价连接而锚定在细胞表面。在识别蛋白质COOH末端的信号后，GPI锚定被添加到内质网中的蛋白质上。我们发现，通过插入蛋白质COOH末端的合成聚合物Ser3-Thr8-Leu14可以完全重建GPI锚定信号，但Thr11-Leu14则不能。这与之前的报道一致，即GPI附着位点需要一个小氨基酸，如Ser、Gly或Ala，而不是Thr。对合成氨基酸序列的分析确定了GPI锚定的一个基本的三部分信号：一个切割/附着结构域，在第一个（GPI锚定附着）和第三个位置需要小氨基酸，但在中间位置特异性较低；一个约8-12个氨基酸的间隔结构域；以及一个至少11个氨基酸的疏水结构域。设计完全合成的GPI锚定信号的能力将允许对该信号的精细结构进行精确探测。
