Collins C, Schappert K, Hayden M R
Department of Medical Genetics, University of British Columbia, Vancouver, Canada.
Hum Mol Genet. 1992 Dec;1(9):727-33.
Myosin participates in a varying repertoire of cellular functions ranging from cytokinesis, receptor capping and secretion to sarcomere contraction. In vertebrates this functional complexity is achieved through the regulated expression of gene families encoding isoproteins for each of the myosin subunits. We report here the identification and characterization of a gene (MYL5) that encodes a novel regulatory myosin light chain isoprotein and maps 700 kb from the human chromosome 4p telomere. Identical cDNAs have been isolated from human adult retina and fetal muscle cDNA libraries. A full length 519 bp open reading frame was identified in the cDNA sequence encoding a predicted protein of 173 residues. Sequence analysis of a 5.6 kb genomic region that encodes these cDNAs revealed the presence of 7 exons which span 4 kb. Expression of this gene has been detected in human adult retina, cerebellum, basal ganglia and fetal skeletal muscle. Whereas Northern analysis fails to detect transcription of this gene in human adult skeletal muscle it reveals an abundant transcript in monkey skeletal muscle. Phylogenetic comparison of the predicted proteins primary structure to those of related myosin light chains from Drosophila, rat and human reveal evolutionarily conserved structural motifs important for both calcium binding and phosphorylation.
肌球蛋白参与多种细胞功能，范围从胞质分裂、受体加帽和分泌到肌节收缩。在脊椎动物中，这种功能的复杂性是通过编码每个肌球蛋白亚基同工蛋白的基因家族的调控表达来实现的。我们在此报告一个基因（MYL5）的鉴定和特征，该基因编码一种新型调节性肌球蛋白轻链同工蛋白，定位于距人类染色体4p端粒700 kb处。已从成人视网膜和胎儿肌肉cDNA文库中分离出相同的cDNA。在编码173个残基的预测蛋白的cDNA序列中鉴定出一个全长519 bp的开放阅读框。对编码这些cDNA的5.6 kb基因组区域的序列分析显示存在7个外显子，跨度为4 kb。该基因已在成人视网膜、小脑、基底神经节和胎儿骨骼肌中检测到表达。虽然Northern分析未能在成人骨骼肌中检测到该基因的转录，但在猴骨骼肌中发现了丰富的转录本。将预测蛋白的一级结构与来自果蝇、大鼠和人类的相关肌球蛋白轻链的一级结构进行系统发育比较，揭示了对钙结合和磷酸化都很重要的进化保守结构基序。
