McCormack Elizabeth, Braam Janet
Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005-1892, USA.
New Phytol. 2003 Sep;159(3):585-598. doi: 10.1046/j.1469-8137.2003.00845.x.
• Calcium (Ca ) signaling is thought to orchestrate responses to cellular stimuli. The efficacy of Ca signaling requires mediation by Ca -binding proteins. • The determination of the Arabidopsis genome sequence enables the identification of genes encoding potential Ca sensors. • Six Arabidopsis loci are defined as calmodulin (CAM) genes. Fifty additional genes are CAM-like (CML) genes, encoding proteins composed mostly of EF-hand Ca -binding motifs, have no other identifiable functional domains, and at least 16% identical with CaM. Number and structural diversity of the EF hands are evaluated. Intron/exon boundaries, phylogenetic tree and chromosomal distribution data for the CAMs and CMLs are presented. • Arabidopsis has 6 CAM genes, encoding only 3 isoforms. Maintenance of these genes suggests that they are unlikely to be fully redundant in function. Furthermore, the repeated EF hand motif is incorporated into at least 50 additional loci. The CaM relatives have altered EF hand number, organization, and predicted functional capacity. Additional structural differences and expression behaviors also indicate that the CML family has likely evolved distinct roles from the CAMs.
• 钙（Ca²⁺）信号传导被认为能协调细胞对刺激的反应。Ca²⁺信号传导的有效性需要钙结合蛋白的介导。
• 拟南芥基因组序列的确定使得能够鉴定出编码潜在钙传感器的基因。
• 六个拟南芥基因座被定义为钙调蛋白（CAM）基因。另外还有五十个基因是类钙调蛋白（CML）基因，它们编码的蛋白质主要由EF手型钙结合基序组成，没有其他可识别的功能结构域，并且与钙调蛋白至少有16%的同源性。对EF手型的数量和结构多样性进行了评估。给出了CAM和CML的内含子/外显子边界、系统发育树和染色体分布数据。
• 拟南芥有6个CAM基因，仅编码3种异构体。这些基因的保留表明它们在功能上不太可能完全冗余。此外，重复的EF手型基序至少还存在于另外五十个基因座中。钙调蛋白相关蛋白的EF手型数量、排列和预测的功能能力都有所改变。其他结构差异和表达行为也表明CML家族可能已经从CAM家族中演化出了不同的作用。
