Aloni-Grinstein R, Seddon A, Yayon A
Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel.
Mol Biotechnol. 1999 Jun;11(3):213-20. doi: 10.1007/BF02788679.
Fibroblast growth factors (FGF) activate their receptors through the formation of trimolecular complexes, composed of a ligand, a receptor, and a heparan sulfate oligosaccharide, all of which are members of particularly large families capable of multiple interactions in a combinatorial fashion. Understanding this large network of interactions not only presents a great challenge, but is practically beyond the capacity of most classical techniques routinely used to study ligand receptor interactions. We have used the yeast two hybrid system to study protein-protein interactions in the FGF family. Both ligand and receptor ectodomains are properly folded and functional in the yeast. Basic FGF (bFGF) expressed in the yeast dimerizes spontaneously. This self-assembly occurs at low affinity, which can be greatly enhanced by the introduction of heparin, supporting a defined role for heparin in bFGF dimerization. Screening a rat embryo cDNA library with bFGF in the yeast two hybrid system identified a short variant of FGF receptor 1, found most frequently in embryonal and tumor cells and which possesses affinity toward bFGF that is significantly greater than that of the more abundant, full-length receptor. We find the yeast two hybrid system, a most suitable alternative method for the analysis of growth factor-receptor interactions as well as for screening for novel interacting proteins and modulators of FGF and its receptors.
成纤维细胞生长因子（FGF）通过形成由配体、受体和硫酸乙酰肝素寡糖组成的三分子复合物来激活其受体，所有这些都是能够以组合方式进行多种相互作用的特别大家族的成员。理解这个庞大的相互作用网络不仅带来了巨大挑战，而且实际上超出了大多数常用于研究配体 - 受体相互作用的经典技术的能力范围。我们使用酵母双杂交系统来研究FGF家族中的蛋白质 - 蛋白质相互作用。配体和受体胞外域在酵母中都能正确折叠并发挥功能。在酵母中表达的碱性FGF（bFGF）会自发二聚化。这种自组装以低亲和力发生，通过引入肝素可大大增强，这支持了肝素在bFGF二聚化中的明确作用。在酵母双杂交系统中用bFGF筛选大鼠胚胎cDNA文库，鉴定出一种FGF受体1的短变体，它最常见于胚胎和肿瘤细胞中，并且对bFGF的亲和力明显大于更丰富的全长受体。我们发现酵母双杂交系统是分析生长因子 - 受体相互作用以及筛选FGF及其受体的新型相互作用蛋白和调节剂的最合适替代方法。
