Caspase-3-mediated cleavage of Akt: Involvement of non-consensus sites and influence of phosphorylation

Here, we show for the first time that Akt1 is cleaved in vitro at the caspase-3 consensus site DQDD456 ↓ SM. Our data suggest QEEE116 ↓ E117 ↓ MD, EEMD119↓, TPPD453 ↓ QD and DAKE398 ↓ IM as novel non-consensus caspase-3 cleavage sites. More importantly, we demonstrate that phosphorylation of Akt1 modulates its cleavage in a site-specific manner: Resistance to cleavage at site DAKE398 (within the kinase domain) in response to phosphorylation suggests a possible mechanism by which the anti-apoptotic role of Akt1 is regulated. Our result is important in biological models which rely on Akt1 for cell survival.