Biosignal Research Center, Kobe University, Kobe 657-8501, Japan.
FEBS Lett. 2012 Jun 4;586(11):1612-6. doi: 10.1016/j.febslet.2012.04.056. Epub 2012 May 11.
X-linked inhibitor of apoptosis protein (XIAP) is a potent antagonist of caspases, and functions as a ubiquitin-E3 ligase by itself and for caspases. Recently, NEDD8, a ubiquitin-like modifier, has been suggested to be used for modification of caspase-7 mediated by XIAP. However, it is not clear whether caspase-7 is a bona fide target for NEDD8. Here we showed that no neddylation of caspase-7 but that of XIAP itself was observed under the conditions in which caspase-7 was modified with ubiquitin. These results reveal that XIAP does not function as a NEDD8-E3 ligase for caspase-7 in vivo.
X 连锁凋亡抑制蛋白（XIAP）是一种有效的胱天蛋白酶抑制剂，它本身和作为胱天蛋白酶的泛素 E3 连接酶发挥作用。最近，NEDD8（一种泛素样修饰物）已被提议用于 XIAP 介导的胱天蛋白酶-7 的修饰。然而，胱天蛋白酶-7 是否是 NEDD8 的真正靶标尚不清楚。在这里，我们发现在胱天蛋白酶-7 被泛素修饰的条件下，没有观察到胱天蛋白酶-7 的 neddylation，但观察到了 XIAP 自身的 neddylation。这些结果表明，XIAP 不在体内作为胱天蛋白酶-7 的 NEDD8-E3 连接酶发挥作用。
