Cloning of the human homolog of mouse transmembrane tryptase

Background: Three functionally distinct tryptases have been identified in the mouse, one of which encodes an unusual protease that possesses a membrane-spanning domain located in its C terminus. Methods and Results: Using the deduced nucleotide sequence of this mouse transmembrane tryptase (mTMT) gene in a polymerase chain reaction approach, cDNAs were isolated from a number of tissues which encode its human homolog. The amino acid sequences of hTMT and mTMT are 74% identical, and the human tryptase also has the novel membrane-spanning domain. Conclusion: The discovery that the human genome contains a large number of homologous, but distinct, tryptase genes suggests that the individual members of this family of proteases evolved to carry out discrete functions in mast cell-mediated allergic reactions.