Molecular Biology and Genetics of Calmodulin in Paramecium

本文对草履虫中钙调素进行了研究。 它将扩展以前的观察，即在一个点突变， 钙调素使草履虫向后游。钙调蛋白 参与钙调节钾通道和细胞活力 在这个有机体中。将制备其他突变钙调素， 将检测它们对钡离子的敏感性;突变体CAM 1 已被证明对钡的敏感性增加，这可以 取代钙在其四个结合位点。基因间抑制基因 将寻找钙调素突变体CAM 1和CAM 11， 寻找其他参与调节离子通道的基因， 细胞活力基因内和基因间抑制因子影响 钙依赖性钾通道激活 将寻求与钡灵敏度的差异。蛋白 其与野生型草履虫钙调蛋白的结合优于其突变体 将在哺乳动物细胞中寻找钙调素， 这些蛋白质的编码将被分离。 钙调素是一种存在于所有细胞类型中的蛋白质， 已经检查过了。它与钙结合， 细胞功能的许多方面。 这其中包括 调节允许离子进入细胞的通道， 调节细胞周期。在原生动物草履虫中， 单个氨基酸的突变已被证明会导致 生物体向后游。此外，这种突变增加了 生物体对钡的敏感性，钡可以替代 钙在特定的结合位点。该提案涉及到一项搜索 对于其他钙调素突变体，通过各种技术， 寻找蛋白质的基因间抑制因子，以及寻找 哺乳动物细胞中与野生型和 原生动物的突变钙调素蛋白质不影响 钙依赖性钾通道的激活， 影响钙调蛋白结合钡的能力也将是 寻找。这项研究应该增加对钙调素如何 调节细胞过程。

This proposal is an investigation of calmodulin in Paramecium. It will extend the previous observation that a point mutation in calmodulin causes the Paramecium to swim backward. Calmodulin is involved in calcium-regulated potassium channels and cell viability in this organism. Other mutant calmodulins will be prepared and their sensitivity to barium ions will be examined; the mutant cam1 has been shown to have increased sensitivity to barium, which can replace calcium in its four binding sites. Intergenic suppressors of the calmodulin mutants cam1 and cam 11 will be sought, to try to find other genes involved in the regulation of ion channels and cell viability. Intragenic and intergenic suppressors which affect activation of the calcium-dependent potassium channel differentially from the barium sensitivity will be sought. Proteins which bind wild-type Paramecium calmodulin better than its mutant calmodulins will be searched for in mammalian cells, and the genes coding for these proteins will be isolated. Calmodulin is a protein which is present in all cell types which have been examined. It binds calcium and is involved in regulation of many aspects of cellular function. Among these are the regulation of channels which permit entry of ions into cells and regulation of the cell cycle. In the protozoan Paramecium, a mutation in a single amino acid has been shown to cause the organism to swim backward. In addition, this mutation increases the sensitivity of the organism to barium, which can substitute for calcium at specific binding sites. The proposal involves a search for additional calmodulin mutants by a variety of techniques, a search for intergenic suppressors of the proteins, and a search for proteins in mammalian cells which bind differently to wild-type and mutant calmodulins from the protozoan. Proteins which do not affect the activation of the calcium-dependent potassium channel but do affect the ability of calmodulin to bind barium will also be sought. The study should increase understanding of how calmodulin regulates cell processes.