Cimler B M, Andreasen T J, Andreasen K I, Storm D R
J Biol Chem. 1985 Sep 5;260(19):10784-8.
P-57 is a novel calmodulin-binding protein which has recently been isolated from bovine cerebral cortex (Andreasen, T. J., Luetje, C. W., Heideman, W., and Storm, D. R. (1983) Biochemistry 22, 4615-4618). In contrast to all other calmodulin-binding proteins characterized thus far, P-57 has equivalent or higher affinity for calmodulin in the absence of free Ca2+ compared to the presence of Ca2+. In this study, the distribution of P-57 in other tissues and within brain was examined using a radioimmune assay and photoaffinity labeling with azido-125I-calmodulin. P-57 was not found in tissues other than brain, retina, and spinal cord. Within brain, P-57 levels varied from 0.1% of the total protein in white matter regions to about 0.5% in cell body-rich fractions. The protein was found in both membrane and soluble fractions. P-57 is the most abundant calmodulin-binding protein in brain and appears to be neural specific. The concentrations of P-57 in brain and its affinity for calmodulin in the absence of Ca2+ are sufficient to complex a significant fraction of the total calmodulin present.
P - 57是一种新型钙调蛋白结合蛋白，最近从牛大脑皮层中分离得到（安德烈亚森，T. J.，卢特杰，C. W.，海德曼，W.，和斯托姆，D. R.（1983年）《生物化学》22卷，4615 - 4618页）。与迄今为止已鉴定的所有其他钙调蛋白结合蛋白不同，与存在Ca2 + 时相比，P - 57在无游离Ca2 + 时对钙调蛋白具有同等或更高的亲和力。在本研究中，使用放射免疫测定法和用叠氮基 - 125I - 钙调蛋白进行光亲和标记，检测了P - 57在其他组织和脑内的分布。除了脑、视网膜和脊髓外，在其他组织中未发现P - 57。在脑内，P - 57水平在白质区域占总蛋白的0.1%至富含细胞体的部分中约为0.5%之间变化。该蛋白在膜组分和可溶性组分中均有发现。P - 57是脑中最丰富的钙调蛋白结合蛋白，似乎具有神经特异性。脑内P - 57的浓度及其在无Ca2 + 时对钙调蛋白的亲和力足以结合相当一部分存在的总钙调蛋白。
