CLONING AND EXPRESSION OF A 2ND HUMAN NATURAL-KILLER-CELL GRANULE TRYPTASE, HNK-TRYP-2 GRANZYME-3/

Cytotoxic lymphocytes possess a number of serine proteases (granzymes) usually localized in cytoplasmic granules. To date, the DNA sequences of four human granzymes have been reported, A fifth human granzyme (g ranzyme 3) has been biochemically purified and its N-terminal amino ac id sequence has been reported, This enzyme was described as possessing tryptase activity, cleaving synthetic substrates after arginine or ly sine, We recently cloned a rat granzyme tryptase (RNK-Tryp-2), and use d this cDNA to screen human cDNA libraries. Isolation of cDNA fragment s of a human gene could be overlapped to provide a complete cDNA seque nce, which we designated HNK-Tryp-2. The N-terminal amino acid sequenc e deduced from HNK-Tryp-2 was identical to that reported for granzyme 3, This gene appears to be a single copy gene that is expressed in iso lated natural killer cells and T cells as well as in tissues containin g these cells.