Scarmato P, Kirchhausen T
Department of Anatomy and Cellular Biology, Harvard Medical School, Boston, Massachusetts 02115.
J Biol Chem. 1990 Mar 5;265(7):3661-8.
Clathrin light chains are extended molecules located along the proximal segment of each of the three heavy chain legs of a clathrin trimer. All mammalian light chains share a central segment with 10 repeated heptad motifs believed to mediate the interaction with clathrin heavy chains. In order to test this model in more detail, we have expressed intact rat liver clathrin light chain LCB3 in Escherichia coli and find that it binds tightly to calf clathrin heavy chains. Using a set of expressed truncated mutants of LCB3, we show that the presence of seven to eight heptads is indeed necessary for a successful interaction. More extensive deletions of the central segment completely abolish the ability to bind to heavy chains. Neither the amino- nor the carboxyl-terminal domain is essential for binding, but competition experiments show that the presence of the carboxyl-terminal domain does enhance the interaction with heavy chains.
网格蛋白轻链是沿着网格蛋白三聚体三条重链腿近端部分分布的延伸分子。所有哺乳动物轻链都有一个中央片段，其中有10个重复的七肽基序，据信这些基序介导与网格蛋白重链的相互作用。为了更详细地测试该模型，我们在大肠杆菌中表达了完整的大鼠肝脏网格蛋白轻链LCB3，并发现它与小牛网格蛋白重链紧密结合。使用一组表达的LCB3截短突变体，我们表明七到八个七肽的存在对于成功相互作用确实是必要的。中央片段更广泛的缺失完全消除了与重链结合的能力。氨基末端和羧基末端结构域对于结合都不是必需的，但竞争实验表明羧基末端结构域的存在确实增强了与重链的相互作用。
