Nilsson I, Sääf A, Whitley P, Gafvelin G, Waller C, von Heijne G
Department of Biochemistry, Stockholm University, Stockholm, S-106 91, Sweden.
J Mol Biol. 1998 Dec 11;284(4):1165-75. doi: 10.1006/jmbi.1998.2217.
alpha-Helix formation in globular proteins has been studied both theoretically and experimentally for decades, while a lack of both high-resolution structures and suitable experimental techniques has hampered the study of helices in membrane proteins. We have developed a new experimental approach, glycosylation mapping, where the active site of the lumenally exposed endoplasmic reticulum enzyme oligosaccharyl transferase is used as a point of reference against which the position of a transmembrane segment in the membrane can be measured. Here, we report an initial analysis of the helix-breaking properties of proline residues inserted in a transmembrane helix. We find that proline residues can break a transmembrane helix, but only when inserted near the end, and only when the helix is sufficiently long. The glycosylation mapping technique may be generally useful for determining the position of transmembrane helices in the membrane.
几十年来，人们一直在理论和实验上研究球状蛋白质中的α螺旋形成，而缺乏高分辨率结构和合适的实验技术阻碍了对膜蛋白中螺旋的研究。我们开发了一种新的实验方法——糖基化图谱分析，其中内质网腔内暴露的寡糖基转移酶的活性位点被用作参考点，据此可以测量膜中跨膜片段的位置。在此，我们报告了对插入跨膜螺旋中的脯氨酸残基的螺旋破坏特性的初步分析。我们发现脯氨酸残基可以破坏跨膜螺旋，但仅当在靠近末端插入时，并且仅当螺旋足够长时。糖基化图谱分析技术可能普遍有助于确定膜中跨膜螺旋的位置。
