FIG. 8.

Electrostatic interactions may contribute to the function of other granzymes. (A) Regions homologous to cs1 and cs2 (boxed) in other human and mouse granzymes. Positively charged amino acids are indicated in bold. (B) GrA binds GAGs. A 50 nM concentration of recombinant mouse GrA was used as described in the legend to Fig. 2A. (C) Heparin abrogates GrA and perforin-mediated killing of Jurkat cells. Recombinant GrA was preincubated at 37°C for 30 min with a 50-fold molar excess of heparin and then used in the in vitro killing assay (see Fig. 1A for details.) Heparin was maintained at at least a fivefold excess over GrA levels during exposure to cells.