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. 2006 Nov 20;175(4):619–630. doi: 10.1083/jcb.200606073

Figure 7.

Figure 7.

Mouse but not human GrA induces perforin-dependent cell death. (A) Progress curves of mGrA (closed boxes) and hGrA (open boxes) cleaving benzyloxy-carbonyl-Lys-thiobenzyl ester, where 1 U of enzyme increases absorbance by 1 milli-OD/min. mGrA contains 144 ± 5 U/μg, whereas hGrA contains 18 ± 2 U/μg. This is consistent with the difference in kcat/KM previously reported (Odake et al., 1991), confirming that the enzymes are equally active. (B) 300 ng of recombinant hGrA was added to LSB with or without DTT and then boiled for 5 min before 10% gel SDS-PAGE and immunoblotting for hGrA. The image shows separated lanes originating from the same gel. (C) Human Jurkat cells or mouse lymphoma cells were incubated for 1 h with recombinant mGrA or recombinant hGrA in the presence or absence of perforin (Pf). Cell survival was assessed 24 h later by MTT assay. (D) HeLa cells were incubated for 4 h with recombinant hGrB, recombinant mGrA, or native hGrA in perforin. Cell survival was assessed by 51Cr release assay. Error bars indicate standard deviation (n = 8).