Study on the myosin like protein from brwn alga Laminaria japonica

从海带（Laminaria japonica）中克隆了一个编码肌球蛋白样蛋白（myosin-like protein，LjMLP）的cDNA。LjMLP由634个氨基酸组成，与其他物种肌球蛋白的马达结构域序列有很大的同源性，但没有与其他肌球蛋白的loop-2、converter、neck和tail结构域对应的区域。重组LjMLP（rLjMLP）在昆虫细胞中表达并在不存在或存在L.粳稻钙调素（LjCaM）。当rLjMLP与rLjCaM共表达时，纯化的rLjMLP显示肌动蛋白激活的Mg-ATPase和肌动蛋白转位活性。rLjCaM在25℃和40μM F-actin存在下表现出最高的Mg-ATPase活性（0.68 l/sec）。在体外运动实验中，25℃时肌动蛋白运动速度为0.03μm/sec。基因组DNA分析表明LjMLP基因由4个外显子和3个内含子组成。RT-PCR分析表明，LjMLP基因的表达与栽培季节无关。日本。

A cDNA encoding myosin-like protein(LjMLP)was cloned from brown alga Laminaria japonica. LjMLP consists of 634 amino acids, which showed the significant homology with sequences of other species myosin motor domain, but there is no region corresponding to loop-2, converter, neck, and tail domains of other myosins in LjMLP. Recombinant LjMLP(rLjMLP)was expressed in insect cells and purified in the absence or presence of L. japonica calmodulin (LjCaM). When rLjMLP was co-expressed with rLjCaM, purified rLjMLP showed that actin-activated Mg-ATPase and actin translocation activities. rLjCaM showed the highest Mg-ATPase activity(0.68 1/sec)at 25℃ in the presence of 40μM F-actin. Actin movement was observed with the velocity of 0.03μm/sec at 25℃ in in vitro motility assay. Genomic DNA analysis revealed LjMLP gene was comprised of four exons interleaved with three introns. According to RT-PCR analysis, mRNA of LjMLP was expressed independent of cultivated-season of L. japonica.