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肌球蛋白轻链是构成鱼类肌纤维主要组成部分,在鱼类肌肉生长和收缩过程中具有重要作用。鳜鱼具有生长快、肉质细嫩、味道鲜美、营养成分高等优良的性状。研究通过构建鳜肌肉组织cDNA文库分离到两个碱性肌球蛋白轻链基因,即MLC1和MLC3基因。序列分析显示MLC1和MLC3基因cDNA序列全长分别为1237bp和1070bp,分别编码192和150个氨基酸,除去MLC1N端多出的42个氨基酸残基,MLC1与MLC3氨基酸序列同源性为80.3%。通过PROSITEtools软件预测显示两种轻链都具有两个保守的EF-手相结构,其中第二个EF-hand结构除前三个氨基酸外同源性达100%。鱼类MLC3轻链N端没有高等脊椎动物MLC3特有标志序列。采用实时荧光定量PCR方法对鳜鱼MLC1和MLC3发育性表达分析表明,在原肠期开始有低量表达,与原肠期、尾芽期和肌肉效应期相比,心搏期和仔鱼期MLC1和MLC3表达量显著升高。研究结果首次提供了鳜肌肉组织肌球蛋白主要结构基因的分子生物学信息以及它们在鳜肌肉组织发生和功能的相关性。
Myosin light chain constitutes a major component of fish muscle fibers, fish muscle growth and contraction plays an important role. Catfish with fast-growing, delicate meat, delicious, high nutritional content of superior traits. Two muscarinic light chain genes, the MLC1 and MLC3 genes, were isolated from the muscular tissue cDNA library. Sequence analysis showed that the full-length cDNA sequences of MLC1 and MLC3 genes were 1237bp and 1070bp, encoding 192 and 150 amino acids, respectively. The MLC1 and MLC3 shared 42.3% more amino acids except MLC1. Prediction by PROSITEtools software showed that both light chains have two conserved EF-phased structures, with the second EF-hand structure having 100% homology outside the first three amino acids. There is no MLC3-specific marker sequence for higher vertebrates in the N-terminus of the fish MLC3 light chain. The analysis of the developmental expression of MLC1 and MLC3 by real-time fluorescence quantitative PCR showed that there was a low expression at the beginning of gastrula. Compared with the stages of gastrula, tail bud and muscle, MLC3 expression increased significantly. The results provide, for the first time, molecular biological information on the major structural genes of muscle myoblasts and their correlation with function and development in musculus.