Wu R Y, Gill G N
Department of Biology, University of California San Diego, La Jolla 92093-0650.
J Biol Chem. 1994 Oct 7;269(40):25085-90.
Endocytosis of cell surface receptors requires sequence "codes" consisting of tight turn structures with an essential Tyr or Phe residue. To determine mechanisms through which cells recognize this information, we utilized exon 16 of the human insulin receptor in the two-hybrid system to isolate a novel 455-amino acid cytoplasmic protein that contains two LIM domains within its carboxyl terminus. Mutational analyses indicate that one of the Cys-rich Zn2+ binding LIM domains specifically recognizes active but not inactive endocytic codes contained in exon 16. These findings suggest that LIM domain structures in proteins provide molecular recognition of Tyr-containing tight turn structures.
细胞表面受体的内吞作用需要由带有必需酪氨酸（Tyr）或苯丙氨酸（Phe）残基的紧密转角结构组成的序列“密码”。为了确定细胞识别该信息的机制，我们在双杂交系统中利用人胰岛素受体的第16外显子分离出一种新的455个氨基酸的细胞质蛋白，其羧基末端含有两个LIM结构域。突变分析表明，富含半胱氨酸的锌离子结合LIM结构域之一特异性识别第16外显子中包含的活性而非无活性的内吞密码。这些发现表明，蛋白质中的LIM结构域结构提供了对含酪氨酸紧密转角结构的分子识别。
