DISSECTING PROCESSING AND APOPTOTIC ACTIVITY OF A CYSTEINE PROTEASE BY MUTANT ANALYSIS

We have compared the behavior of wild-type mouse NEDD-2, a (n) under b ar eural precursor cell-(e) under bar xpressed, (d) under bar evelopme ntally (d) under bar own-regulated cysteine protease gene, to various mutant forms of the gene in both apoptotic activity in neuronal cells and proteolytic cleavage in the Semliki Forest virus and rabbit reticu locyte protein expression systems. Our results confirm that NEDD-2 pro cessing and apoptotic activity are linked phenomena. They identify asp artate residues as likely targets for autocatalytic cleavage. They est ablish that cleavage events only occur at specific sites. Finally, the y pinpoint differential effects of individual mutations on the overall proteolytic cleavage patterns, raising interesting questions related to the mechanisms of subunit assembly.