Wizemann Harald, Garbe Jörg H O, Friedrich Martin V K, Timpl Rupert, Sasaki Takako, Hohenester Erhard
Max-Planck-Institut für Biochemie, D-82152, Martinsried, Germany.
J Mol Biol. 2003 Sep 19;332(3):635-42. doi: 10.1016/s0022-2836(03)00848-9.
Laminin-2 (alpha2beta1gamma1) is found in basement membranes surrounding muscle and peripheral nerve cells. Several types of cellular receptors bind to the laminin G-like (LG) domains at the C terminus of the alpha2 chain, the interaction with alpha-dystroglycan (alpha-DG) being particularly important in muscle. We have used site-directed mutagenesis and in vitro binding assays to map the binding sites on the laminin alpha2 chain LG4-LG5 domain pair for alpha-DG, heparin and sulfatides. Calcium-dependent alpha-DG recognition requires the calcium ion in LG4, but not the one in LG5, as well as basic residues in both LG domains. Heparin and sulfatides also bind to basic residues in both LG domains, but there is little overlap in the binding sites for alpha-DG and heparin/sulfatides. The results should prove useful for the molecular dissection of laminin-receptor interactions in vivo.
层粘连蛋白-2（α2β1γ1）存在于肌肉和周围神经细胞周围的基底膜中。几种细胞受体与α2链C端的层粘连蛋白G样（LG）结构域结合，其中与α- dystroglycan（α-DG）的相互作用在肌肉中尤为重要。我们利用定点诱变和体外结合试验来确定层粘连蛋白α2链LG4-LG5结构域对与α-DG、肝素和硫苷脂的结合位点。钙依赖性α-DG识别需要LG4中的钙离子，但不需要LG5中的钙离子，以及两个LG结构域中的碱性残基。肝素和硫苷脂也与两个LG结构域中的碱性残基结合，但α-DG与肝素/硫苷脂的结合位点几乎没有重叠。这些结果将有助于体内层粘连蛋白-受体相互作用的分子解析。
