Identification of CD44 residues important for hyaluronan binding and delineation of the binding site
Identification of CD44 residues important for hyaluronan binding and delineation of the binding site
复制标题
DOI：
10.1074/jbc.273.1.338
复制
发表时间：
1998-01-02
影响因子：
4.8
通讯作者：
Aruffo, A
中科院分区：
文献类型：
--
作者：
Bajorath, J;Greenfield, B;Aruffo, A
CD44是一种广泛分布的细胞表面蛋白，在细胞粘附和迁移中起作用。作为一种蛋白聚糖，CD44还与生长因子和趋化因子的结合和呈递有关。CD44的细胞外区域可变剪接，产生多种CD44亚型。所有同种异构体都含有氨基末端结构域，这与软骨连接蛋白是同源的。CD44的软骨连接蛋白样结构域对透明质酸结合很重要。用MMR测定了TSG-6连接蛋白结构域的结构。基于该结构，构建了CD44的链接同源区分子模型，利用该模型选择位点特异性突变的残基，以确定配体结合的重要残基，并勾勒出透明质酸结合位点。产生并鉴定了24个点突变体，并确定了8个残基对结合或支持相互作用至关重要。在该模型中，这些残基形成了一个连贯的表面，其位置大致对应于两个功能无关的钙依赖性凝集素，甘露糖结合蛋白和e-选择素（CD62E）中的碳水化合物结合位点。
CD44 is a widely distributed cell surface protein that plays a role in cell adhesion and migration. As a proteoglycan, CD44 is also implicated in growth factor and chemokine binding and presentation, The extracellular region of CD44 is variably spliced, giving rise to multiple CD44 isoforms. All isoforms contain an amino-terminal domain, which is homologous to cartilage link proteins. The cartilage link protein-like domain of CD44 is important for hyaluronan binding. The structure of the link protein domain of TSG-6 has been determined by MMR. Based on this structure, a molecular model of the link-homologous region of CD44 was constructed, This model was used to select residues for site-specific mutagenesis in an effort to identify residues important for ligand binding and to outline the hyaluronan binding site. Twenty-four point mutants were generated and characterized, and eight residues were identified as critical for binding or to support the interaction. In the model, these residues form a coherent surface the location of which approximately corresponds to the carbohydrate binding sites in two functionally unrelated calcium-dependent lectins, mannose-binding protein and E-selectin (CD62E).