cDNA cloning, genomic structure, and chromosome mapping of the human epithelial membrane protein CL-20 gene (EMP1), a member of the PMP22 family.
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.
Chen
Y
Y
Cell Biology Section, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
Medvedev
A
A
Ruzanov
P
P
Marvin
K W
KW
Jetten
A M
AM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics; D003001:Cloning, Molecular; D017124:Conserved Sequence; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics*; D004848:Epithelium / Q000378:metabolism; D005091:Exons; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007438:Introns; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009185:Myelin Proteins / Q000235:genetics*; D009363:Neoplasm Proteins; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D011956:Receptors, Cell Surface; D012176:Retinoids / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014018:Tissue Distribution
D017931:DNA Primers; D018076:DNA, Complementary; D008565:Membrane Proteins; D009185:Myelin Proteins; D009363:Neoplasm Proteins; C073687:PMP22 protein, human; C489546:Pmp22 protein, rat; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D012176:Retinoids; C097051:epithelial membrane protein-1