Davis-Smyth T, Presta L G, Ferrara N
Departments of Cardiovascular Research, Genentech, Inc., South San Francisco, California 94080, USA.
J Biol Chem. 1998 Feb 6;273(6):3216-22. doi: 10.1074/jbc.273.6.3216.
Flt-1 is one of two receptor tyrosine kinases through which the angiogenic factor vascular endothelial growth factor (VEGF) functions. Placenta growth factor (PlGF) is an additional ligand for Flt-1. The second immunoglobulin-like domain in the extracellular domain of Flt-1 has previously been identified as the region containing the critical ligand-binding determinants. We analyzed the contribution of charged residues within the first three domains of Flt-1 to ligand binding by alanine-scanning mutagenesis. Domain 2 residues Arg159, Glu208 and His223-Arg224 (together) affect both VEGF and PlGF binding, while Glu137, Lys171, His223, and Arg224 affect PlGF but not VEGF. Several charged residues, especially Asp187, are important in maintaining the structural integrity of domain 2. In addition, some residues in domain 3 contribute to binding (Asp231) or provide for additional discrimination between ligands (Arg280-Asp283).
Flt-1是血管生成因子血管内皮生长因子（VEGF）发挥作用的两种受体酪氨酸激酶之一。胎盘生长因子（PlGF）是Flt-1的另一种配体。Flt-1胞外结构域中的第二个免疫球蛋白样结构域先前已被确定为包含关键配体结合决定簇的区域。我们通过丙氨酸扫描诱变分析了Flt-1前三个结构域中带电荷残基对配体结合的贡献。结构域2中的残基Arg159、Glu208和His223-Arg224（共同作用）影响VEGF和PlGF的结合，而Glu137、Lys171、His223和Arg224影响PlGF但不影响VEGF。几个带电荷残基，尤其是Asp187，对维持结构域2的结构完整性很重要。此外，结构域3中的一些残基有助于结合（Asp231）或在配体之间提供额外的区分（Arg280-Asp283）。
