Sollerbrant Kerstin, Raschperger Elisabeth, Mirza Momina, Engstrom Ulla, Philipson Lennart, Ljungdahl Per O, Pettersson Ralf F
Ludwig Institute for Cancer Research, Stockholm Branch, Karolinska Intitutet, SE-17177 Stockholm, Sweden.
J Biol Chem. 2003 Feb 28;278(9):7439-44. doi: 10.1074/jbc.M205927200. Epub 2002 Dec 4.
The Coxsackievirus and adenovirus receptor (CAR) functions as a virus receptor, but its primary biological function is unknown. A yeast two-hybrid screen was used to identify Ligand-of-Numb protein-X (LNX) as a binding partner to the intracellular tail of CAR. LNX harbors several protein-protein interacting domains, including four PDZ domains, and was previously shown to bind to and regulate the expression level of the cell-fate determinant Numb. CAR was able to bind LNX both in vivo and in vitro. Efficient binding to LNX required not only the consensus PDZ domain binding motif in the C terminus of CAR but also upstream sequences. The CAR binding region in LNX was mapped to the second PDZ domain. CAR and LNX were also shown to colocalize in vivo in mammalian cells. We speculate that CAR and LNX are part of a larger protein complex that might have important functions at discrete subcellular localizations in the cell.
柯萨奇病毒和腺病毒受体（CAR）作为一种病毒受体，但其主要生物学功能尚不清楚。利用酵母双杂交筛选法鉴定出Numb蛋白配体-X（LNX）是CAR细胞内尾部的结合伴侣。LNX含有多个蛋白质-蛋白质相互作用结构域，包括四个PDZ结构域，先前已证明它能结合并调节细胞命运决定因子Numb的表达水平。CAR在体内和体外均能与LNX结合。与LNX的有效结合不仅需要CAR C末端的共有PDZ结构域结合基序，还需要上游序列。LNX中的CAR结合区域定位于第二个PDZ结构域。CAR和LNX在哺乳动物细胞体内也共定位。我们推测，CAR和LNX是一个更大的蛋白质复合物的一部分，该复合物可能在细胞内离散的亚细胞定位中具有重要功能。
