Trophinin Associated Protein (TROAP)

Proline residues make up 16% of the predicted 778-amino acid tastin protein. One region of the protein contains 4 tandem repeats and is rich in cysteines. In vitro translated tastin has a molecular mass of 80 kD. Immunofluorescence studies with mammalian cells expressing trophinin alone or in combination with tastin indicated that tastin creates multivalent trophinin patches on the cell surface that serve as potent adhesion sites. In both HT-H and SNG-M cells, tastin localized as a diffuse cytoplasmic protein and in fibers, suggesting that it associates with the cytoskeleton. Northern blot analysis revealed that tastin is expressed as a major 3.2- and a minor 3.5-kb mRNA in HT-H and SNG-M cells. However, tastin did not appear to be expressed in various other types of human cells, with the exception of macrophages.