title: Characterization of the novel human transmembrane protein 9 (TMEM9) that localizes to lysosomes and late endosomes.
abstract: We have identified and characterized the novel human transmembrane protein 9 (TMEM9). TMEM9 encodes a 183 amino-acid protein that contains an N-terminal signal peptide, a single transmembrane region, three potential N-glycosylation sites, and three conserved cys-rich domains in the N-terminus, but no hitherto known functional domains. The protein is highly conserved between species from Caenorhabditis elegans to man and belongs to a novel family of transmembrane proteins. The TMEM9 gene consists of at least 6 exons and is localized to chromosome 1q41. TMEM9 mRNA is expressed in a wide range of tissues and cells. COS-1 cells transfected with a TMEM9 expression plasmid gave three bands of about 28, 31, and 33kDa representing glycosylated forms of TMEM9 with a protein backbone of about 26kDa. In COS-1 cells transfected with a TMEM9-GFP expression construct,TMEM9-GFP is co-expressed with LAMP1 on late endosomes and lysosomes as well as on ER. Thus, TMEM9 is a phylogenetically conserved, widely expressed transmembrane protein with a potential, but unknown function in intracellular transport.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D017173:Caenorhabditis elegans / Q000378:metabolism; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D017124:Conserved Sequence; D017931:DNA Primers; D011992:Endosomes / Q000378:metabolism*; D005786:Gene Expression Regulation; D006031:Glycosylation; D006801:Humans; D008247:Lysosomes / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D021382:Protein Sorting Signals; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
chemical_list: D017931:DNA Primers; D008565:Membrane Proteins; D021382:Protein Sorting Signals; C467804:TMEM9 protein, human