Luan Jing, Liu Zhenhui, Zhang Shicui, Li Hongyan, Fan Chunxin, Li Lei
Department of Marine Biology, Ocean University of China, Qingdao 266003, China.
Acta Biochim Biophys Sin (Shanghai). 2007 Apr;39(4):255-64. doi: 10.1111/j.1745-7270.2007.00277.x.
Two full-length cDNAs, named CaM1a and CaM1b, encoding the highly conserved calmodulin1 (CaM1) proteins, were isolated from the cDNA library of amphioxus Branchiostoma belcheri tsingtauense. There are only two nucleotide differences between them, producing one amino acid difference between CaM1a and CaM1b. Comparison of the amino acid sequence of CaM1 reveals that the B. belcheri tsingtauense CaM1a is identical with CaM1 proteins of B. floridae and B. lanceolatum, Drosophila melanogaster CaM, ascidian Halocynthia roretzi CaMA and mollusk Aplysia californica CaM, and CaM1b differs only at one position (138, Asn to Asp). The phylogenetic analysis indicates that the CaM1 in all three amphioxus species appears to encode the conventional CaM and CaM2 might be derived from gene duplication of CaM1. Southern blot suggests that there are two copies of CaM1 in the genome of B. belcheri tsingtauense. Northern blot and in situ hybridization analysis shows the presence of two CaM1 mRNA transcripts with various expression levels in different adult tissues and embryonic stages in amphioxus B. belcheri tsingtauense. The evolution and diversity of metazoan CaM mRNA transcripts are also discussed.
从青岛文昌鱼的cDNA文库中分离出两个全长cDNA，分别命名为CaM1a和CaM1b，它们编码高度保守的钙调蛋白1（CaM1）蛋白。它们之间只有两个核苷酸差异，导致CaM1a和CaM1b之间有一个氨基酸差异。对CaM1氨基酸序列的比较表明，青岛文昌鱼CaM1a与佛罗里达文昌鱼、 lanceolatum文昌鱼、果蝇钙调蛋白、海鞘Halocynthia roretzi CaMA和软体动物加州海兔钙调蛋白相同，而CaM1b仅在一个位置（138位，天冬酰胺到天冬氨酸）不同。系统发育分析表明，所有三种文昌鱼中的CaM1似乎编码传统的CaM，而CaM2可能源自CaM1的基因复制。Southern杂交表明，青岛文昌鱼基因组中有两个CaM1拷贝。Northern杂交和原位杂交分析表明，在青岛文昌鱼的不同成体组织和胚胎阶段存在两种表达水平不同的CaM1 mRNA转录本。还讨论了后生动物CaM mRNA转录本的进化和多样性。
