Saras J, Engström U, Góñez L J, Heldin C H
Ludwig Institute for Cancer Research, Box 595, Biomedical Centre, S-751 24 Uppsala, Sweden.
J Biol Chem. 1997 Aug 22;272(34):20979-81. doi: 10.1074/jbc.272.34.20979.
The intracellular protein-tyrosine phosphatase PTPL1 has five PDZ domains and one of them, PDZ 2, has previously been shown to interact with the C-terminal tail of Fas, a member of the tumor necrosis factor receptor family. Using a peptide binding assay, we show that not only PDZ 2 but also PDZ 4 of PTPL1 interacts with high affinity with peptides derived from the C terminus of Fas. The five most C-terminal amino acid residues of Fas influence the affinity of the interaction. Whereas the glutamine and isoleucine residues in the 4th and 5th positions from the C terminus affect the interaction in a negative and positive manner, respectively, the three C-terminal amino acid residues (SLV) are necessary and sufficient for a high affinity interaction to occur. Both the carboxyl group and side chain of the valine residue at the C terminus of Fas are essential, and the leucine and serine residues in the 2nd and 3rd positions, respectively, from the C terminus are important for the interactions with PDZ 2 and PDZ 4 of PTPL1.
细胞内蛋白酪氨酸磷酸酶PTPL1有五个PDZ结构域，其中一个结构域PDZ 2此前已被证明可与肿瘤坏死因子受体家族成员Fas的C末端尾巴相互作用。通过肽结合试验，我们发现不仅PTPL1的PDZ 2，而且PDZ 4也能与源自Fas C末端的肽以高亲和力相互作用。Fas的五个最末端的氨基酸残基影响相互作用的亲和力。从C末端起第4和第5位的谷氨酰胺和异亮氨酸残基分别以负面和正面方式影响相互作用，而三个C末端氨基酸残基（SLV）对于高亲和力相互作用的发生是必要且充分的。Fas C末端缬氨酸残基的羧基和侧链都是必不可少的，并且从C末端起第2和第3位的亮氨酸和丝氨酸残基对于与PTPL1的PDZ 2和PDZ 4的相互作用很重要。
