Ikegaki N, Minna J, Kennett R H
Department of Human Genetics, University of Pennsylvania, School of Medicine, Philadelphia, 19104.
EMBO J. 1989 Jun;8(6):1793-9. doi: 10.1002/j.1460-2075.1989.tb03573.x.
The L-myc gene is the third member of the myc family of proto-oncogenes. Amplification and elevated expression of the L-myc gene has been detected in a subset of small cell lung carcinoma (SCLC) cell lines. The biological properties and functions of the L-myc gene and its product have not yet been elucidated. Monoclonal antibodies against two myc homology boxes were used to characterize the L-myc gene product. These antibodies react with two groups of polypeptides of apparent masses of 60, 61 and 66 kd (the long forms), and 34 and 37 kd (the short forms) in SCLC cells expressing L-myc transcripts. The long form L-myc proteins are associated with the nuclear fraction of the cells. The short form L-myc proteins are present in the cytoplasmic fraction, though diffusion of the short forms from the nucleus during cell fractionation cannot be ruled out. The half-life of the long form polypeptides is approximately 45-90 min. The short form polypeptides have a half-life of approximately 120-180 min. The L-myc protein is not detectable in the mitotic cells, suggesting that the L-myc protein expression is tightly regulated during the cell cycle.
L-myc基因是原癌基因myc家族的第三个成员。在一部分小细胞肺癌（SCLC）细胞系中检测到了L-myc基因的扩增和表达升高。L-myc基因及其产物的生物学特性和功能尚未阐明。针对两个myc同源框的单克隆抗体被用于鉴定L-myc基因产物。这些抗体与表达L-myc转录本的SCLC细胞中两组表观分子量分别为60、61和66kd（长形式）以及34和37kd（短形式）的多肽发生反应。长形式的L-myc蛋白与细胞的核部分相关。短形式的L-myc蛋白存在于细胞质部分，不过在细胞分级分离过程中短形式从细胞核扩散的可能性也不能排除。长形式多肽的半衰期约为45 - 90分钟。短形式多肽的半衰期约为120 - 180分钟。在有丝分裂细胞中检测不到L-myc蛋白，这表明L-myc蛋白的表达在细胞周期中受到严格调控。
