Molecular characterisation of mouse and human TSSC6: evidence that TSSC6 is a genuine member of the tetraspanin superfamily and is expressed specifically in haematopoietic organs

Previous analyses of the murine and human TSSC6 (also known as Phemx) prote ins were not carried out using the full length sequence. Using 5'-RACE and cDNA library screening, we identified an additional 5' sequence for both th e murine Tssc6 cDNA and its human homologue TSSC6. This novel sequence enco des a 5' exon encoding an in frame, upstream start codon, an N-terminal cyt oplasmic domain and a transmembrane domain. The deduced, and now full lengt h, murine and human TSSC6 proteins contained four hydrophobic regions toget her with other features characteristic of the tetraspanin superfamily. Comp utational analyses of the full length sequences show that TSSC6 is a genuin e, albeit relatively divergent member of this superfamily. Using RNA from a number of mouse tissues, we identified seven splice variants of Tssc6. Spl ice variants of the human gene were also detected. Tssc6 expression was det ected early in embryogenesis in primitive blood cells and was confined to h aematopoietic organs in the adult mouse. Tssc6 expression was detected in m any haematopoietic cell lines and was highest in cell lines of the erythroi d lineage. (C) 2001 Elsevier Science B.V. All rights reserved.