Wang J Y, Frenzel K E, Wen D, Falls D L
Department of Biology, Emory University, Atlanta, Georgia 30322, USA.
J Biol Chem. 1998 Aug 7;273(32):20525-34. doi: 10.1074/jbc.273.32.20525.
The neuregulins are receptor tyrosine kinase ligands that play a critical role in the development of the heart, nervous system, and breast. Unlike many extracellular signaling molecules, such as the neurotrophins, most neuregulins are synthesized as transmembrane proteins. To determine the functions of the highly conserved neuregulin cytoplasmic tail, a yeast two-hybrid screen was performed to identify proteins that interact with the 157-amino acid sequence common to the cytoplasmic tails of all transmembrane neuregulin isoforms. This screen revealed that the neuregulin cytoplasmic tail interacts with the LIM domain region of the nonreceptor protein kinase LIM kinase 1 (LIMK1). Interaction between the neuregulin cytoplasmic tail and full-length LIMK1 was demonstrated by in vitro binding and co-immunoprecipitation assays. Transmembrane neuregulins with each of the three known neuregulin cytoplasmic tail isoforms interacted with LIMK1. In contrast, the cytoplasmic tail of TGF-alpha did not interact with LIMK1. In vivo, neuregulin and LIMK1 are co-localized at the neuromuscular synapse, suggesting that LIMK1, like neuregulin, may play a role in synapse formation and maintenance. To our knowledge, LIMK1 is the first identified protein shown to interact with the cytoplasmic tail of a receptor tyrosine kinase ligand.
神经调节蛋白是受体酪氨酸激酶配体，在心脏、神经系统和乳腺的发育中起关键作用。与许多细胞外信号分子（如神经营养因子）不同，大多数神经调节蛋白是作为跨膜蛋白合成的。为了确定高度保守的神经调节蛋白胞质尾的功能，进行了酵母双杂交筛选，以鉴定与所有跨膜神经调节蛋白异构体胞质尾共有的157个氨基酸序列相互作用的蛋白质。该筛选揭示了神经调节蛋白胞质尾与非受体蛋白激酶LIM激酶1（LIMK1）的LIM结构域区域相互作用。通过体外结合和共免疫沉淀试验证明了神经调节蛋白胞质尾与全长LIMK1之间的相互作用。具有三种已知神经调节蛋白胞质尾异构体中的每一种的跨膜神经调节蛋白都与LIMK1相互作用。相比之下，转化生长因子-α（TGF-α）的胞质尾不与LIMK1相互作用。在体内，神经调节蛋白和LIMK1共定位于神经肌肉突触，这表明LIMK1与神经调节蛋白一样，可能在突触形成和维持中起作用。据我们所知，LIMK1是第一个被鉴定出与受体酪氨酸激酶配体的胞质尾相互作用的蛋白质。
