Post-translational arginylation of proteins in cultured cells

The aim of this study was to analyze the N-terminal post-translational inco rporation of arginine into cytosolic proteins from cultured cells and the i n 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 signific antly the arginylation reaction while the novo synthesis of protein was red uced by 98%. Under these conditions, we found that of the total [C-14]argin ine incorporated into the proteins, around 20% to 40% was incorporated into the N-terminal position of soluble proteins by a post-translational mechan ism. 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% hi gher in apoptotic cells with respect to control cells. These findings sugge st that the post-translational arginylation of proteins may be involved in programmed cell death.