Cloning and expression of a second 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 (granzyme 3) has been biochemically purified and its N-terminal amino acid sequence has been reported. This enzyme was described as possessing tryptase activity, cleaving synthetic substrates after arginine or lysine. We recently cloned a rat granzyme tryptase (RNK-Tryp-2), and used this cDNA to screen human cDNA libraries. Isolation of cDNA fragments of a human gene could be overlapped to provide a complete cDNA sequence, which we designated HNK-Tryp-2. The N-terminal amino acid sequence 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 isolated natural killer cells and T cells as well as in tissues containing these cells.