Chen Y, Medvedev A, Ruzanov P, Marvin K W, Jetten A M
Cell Biology Section, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
Genomics. 1997 Apr 1;41(1):40-8. doi: 10.1006/geno.1997.4524.
CL-20 is a novel gene encoding a protein that is structurally related to but distinct from the peripheral myelin protein PMP22. Like PMP22, CL-20 is likely to play important roles in the regulation of cell proliferation, differentiation, and cell death. In this study, we describe the cloning and sequencing of a cDNA encoding the human homologue of CL-20 and characterize the genomic structure of this gene. The hCL-20 gene (HGMW-approved symbol EMP1) encodes a protein of 157 amino acids that exhibits 76% identity to the rabbit CL-20 and to the rat EMP-1, which have been described recently, and 39% identity to human PMP22. CL-20 contains four hydrophobic domains, suggesting that it is an integral membrane protein. In particular the second hydrophobic domain encoded within the fourth exon is highly conserved among CL-20, EMP-1, and PMP22, suggesting a functional role for this region. CL-20 mRNA is abundant in squamous-differentiated bronchial epithelial cells; however, low levels of CL-20 mRNA can be detected in several human tissues by Northern analysis. Retinoic acid, which inhibits squamous differentiation, represses CL-20 expression in normal human bronchial epithelial cells. The genomic structure of the hCL-20 gene was analyzed using a P1 vector containing this gene. The hCL-20 gene contains five exons about 0.2, 0.12, 0.1, 0.14, and 2.2 kb and four introns about 15, 1.9, 0.1, and 0.7 kb. We have mapped the hCL-20 gene to chromosome 12p12 by fluorescence in situ hybridization.
CL-20是一种编码蛋白质的新基因，该蛋白质在结构上与外周髓磷脂蛋白PMP22相关，但又有所不同。与PMP22一样，CL-20可能在细胞增殖、分化和细胞死亡的调节中发挥重要作用。在本研究中，我们描述了编码CL-20人类同源物的cDNA的克隆和测序，并对该基因的基因组结构进行了表征。hCL-20基因（HGMW批准的符号为EMP1）编码一种由157个氨基酸组成的蛋白质，与最近描述的兔CL-20和大鼠EMP-1具有76%的同一性，与人类PMP22具有39%的同一性。CL-20包含四个疏水结构域，表明它是一种整合膜蛋白。特别是在第四外显子中编码的第二个疏水结构域在CL-20、EMP-1和PMP22中高度保守，表明该区域具有功能作用。CL-20 mRNA在鳞状分化的支气管上皮细胞中丰富；然而，通过Northern分析在几种人类组织中可检测到低水平的CL-20 mRNA。抑制鳞状分化的视黄酸可抑制正常人支气管上皮细胞中CL-20的表达。使用包含该基因的P1载体分析了hCL-20基因的基因组结构。hCL-20基因包含五个外显子，大小约为0.2、0.12、0.1、0.14和2.2 kb，四个内含子，大小约为15、1.9、0.1和0.7 kb。我们通过荧光原位杂交将hCL-20基因定位到12号染色体p12上。
