Post-translational arginylation of proteins in cultured cells.

The aim of this study was to analyze the N-terminal post-translational incorporation of arginine into cytosolic proteins from cultured cells and the in vitro incorporation of arginine into soluble proteins of PC12 cells after serum deprivation. Arginine incorporation was measured in the presence of protein synthesis inhibitors. None of the inhibitors used affected significantly the arginylation reaction while the novo synthesis of protein was reduced by 98%. Under these conditions, we found that of the total [14C]arginine incorporated into the proteins, around 20% to 40% was incorporated into the N-terminal position of soluble proteins by a post-translational mechanism. These results suggest that this post-translational aminoacylation may be a widespread reaction in neuronal and non-neuronal cells. We also found that in PC12 cells, the in vitro post-translational arginylation was 60% higher in apoptotic cells with respect to control cells. These findings suggest that the post-translational arginylation of proteins may be involved in programmed cell death.