Watson N, Williams K L, Alexander S
Division of Biological Sciences, University of Missouri, Columbia 65211.
J Biol Chem. 1993 Oct 25;268(30):22634-41.
The monoclonal antibody MUD50 recognizes an epitope on a family of developmentally regulated proteins in Dictyostelium discoideum (Alexander, S., Smith, E., Davis, L., Gooley, A., Por, S. B., Browne, L., and Williams, K. L. (1988) Differentiation 38, 82-90). This epitope is an O-linked oligosaccharide that requires the wild-type modB allele for expression. These glycoproteins are structurally diverse. Some are integral membrane proteins, while others are soluble and do not require detergent for solubilization. One of the soluble glycoproteins, PsB, is also recognized by the monoclonal antibody MUD102, which binds to the polypeptide backbone. The antibody recognizes a single 100-kDa band in Western analysis. In this report we demonstrate that the PsB molecule is part of a specific developmentally regulated multiprotein complex containing six different proteins. The complex is held together by both covalent and noncovalent bonds. Interestingly, only the PsB glycoprotein has the MUD50 O-linked oligosaccharide determinant. None of the proteins in the complex is N-glycosylated as assessed by sensitivity to peptide N-glycosidase F. Only one of the complex proteins is heavily phosphorylated. This work establishes the foundation for additional studies on the biosynthesis, processing, and assembly of the O-glycosylated PsB protein.
单克隆抗体MUD50识别盘基网柄菌中一类受发育调控的蛋白质上的一个表位（亚历山大，S.，史密斯，E.，戴维斯，L.，古利，A.，波尔，S.B.，布朗，L.，和威廉姆斯，K.L.（1988年）《分化》38卷，第82 - 90页）。这个表位是一个O - 连接寡糖，其表达需要野生型modB等位基因。这些糖蛋白在结构上多种多样。有些是整合膜蛋白，而其他的是可溶性的，溶解时不需要去污剂。其中一种可溶性糖蛋白PsB，也能被单克隆抗体MUD102识别，该抗体与多肽主链结合。在蛋白质免疫印迹分析中，该抗体识别一条单一的100 kDa条带。在本报告中，我们证明PsB分子是一个特定的、受发育调控的多蛋白复合物的一部分，该复合物包含六种不同的蛋白质。该复合物通过共价键和非共价键结合在一起。有趣的是，只有PsB糖蛋白具有MUD50 O - 连接寡糖决定簇。通过对肽N - 糖苷酶F的敏感性评估，复合物中的蛋白质均未进行N - 糖基化。复合物中只有一种蛋白质被大量磷酸化。这项工作为进一步研究O - 糖基化PsB蛋白的生物合成、加工和组装奠定了基础。
