Pasquale E B
Department of Biology, University of California, San Diego, La Jolla 92093.
Cell Regul. 1991 Jul;2(7):523-34. doi: 10.1091/mbc.2.7.523.
Chicken embryo kinase 5 (Cek5) is a transmembrane tyrosine kinase of the Eph family that was identified by screening a 10-d chicken embryo cDNA expression library with anti-phosphotyrosine antibodies. The extracellular region of Cek5 contains a cysteine rich N-terminal subdomain and a C-terminal subdomain mostly devoid of cysteines and comprising two repeats similar to fibronectin type III repeats. Immunoblotting experiments with anti-Cek5 polyclonal antibodies indicated that Cek5 is a membrane-associated 120-kDa protein containing intramolecular (but not intermolecular) disulfide bonds. Cek5 is already expressed in 2-d-old chicken embryos and is also expressed, at higher levels, later in development. In 10-d-old chicken embryos, Cek5 is expressed at substantial levels in nearly all the tissues examined, whereas in adult it is expressed predominantly in the brain. The expression of Cek5 in the brain gradually diminishes during embryonic development, whereas in the skeletal muscle of the thigh a sharp decrease in Cek5 expression was detected at the time of terminal muscle differentiation. Its wide tissue distribution throughout development and its sustained expression in adult brain suggest that Cek5 is an important component of signal transduction pathways, likely to interact with a widely distributed and important ligand, which is as yet unknown.
鸡胚胎激酶5（Cek5）是Eph家族的一种跨膜酪氨酸激酶，它是通过用抗磷酸酪氨酸抗体筛选10日龄鸡胚胎cDNA表达文库而鉴定出来的。Cek5的细胞外区域包含一个富含半胱氨酸的N端亚结构域和一个C端亚结构域，该C端亚结构域几乎不含半胱氨酸，由两个类似于纤连蛋白III型重复序列的重复序列组成。用抗Cek5多克隆抗体进行的免疫印迹实验表明，Cek5是一种与膜相关的120 kDa蛋白，含有分子内（而非分子间）二硫键。Cek5在2日龄鸡胚胎中就已表达，在发育后期也有更高水平的表达。在10日龄鸡胚胎中，Cek5在几乎所有检测的组织中都有大量表达，而在成年鸡中，它主要在脑中表达。Cek5在脑中的表达在胚胎发育过程中逐渐减少，而在大腿骨骼肌中，在终末肌分化时检测到Cek5表达急剧下降。其在整个发育过程中的广泛组织分布以及在成年脑中的持续表达表明，Cek5是信号转导通路的重要组成部分，可能与一种广泛分布且重要的配体相互作用，而该配体目前尚不清楚。
