Characterization of the novel human transmembrane protein 9 (TMEM9) that localizes to lysosomes and late endosomes

Biochem Biophys Res Commun. 2002 Oct 4;297(4):912-7. doi: 10.1016/s0006-291x(02)02228-3.


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

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • COS Cells
  • Caenorhabditis elegans / metabolism
  • Chlorocebus aethiops
  • Cloning, Molecular
  • Conserved Sequence
  • DNA Primers
  • Endosomes / metabolism*
  • Gene Expression Regulation
  • Glycosylation
  • Humans
  • Lysosomes / metabolism*
  • Membrane Proteins / genetics*
  • Membrane Proteins / metabolism*
  • Mice
  • Molecular Sequence Data
  • Polymerase Chain Reaction
  • Protein Sorting Signals
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Transcription, Genetic


  • DNA Primers
  • Membrane Proteins
  • Protein Sorting Signals
  • TMEM9 protein, human

Associated data

  • GENBANK/AY138587