Role of N-myristoylation in stability and subcellular localization of the CLPABP protein.

Cardiolipin and phosphatidic acid-binding protein (CLPABP) controls the stability of the mRNA harboring an AU-rich element (ARE) in the 3' UTR with the help of the RNA stabilizer, human antigen R (HuR). Although CLPABP is localized on the mitochondrial surface as a large protein-RNA complex, its precise role is not yet known. Recently, CLPABP was identified as an N-myristoylated protein. Here, we demonstrate the effects of N-myristoylation on the functions of CLPABP. In the present study, compared to the wild-type protein that possessed the "MG" motif at the N-terminus for N-myristoylation, the mutant CLPABP protein that lacked N-myristoylation modification site was unstable. Furthermore, the expression of the G/A mutant of CLPABP, which lacked N-myristoylation site, induced morphological alterations in mitochondria. Because pleckstrin homology domain-deleted mutant, which was fused with the N-myristoylation site derived from intact CLPABP, could not colocalize with mitochondria, N-myristoylation of CLPABP was predicted to affect its stability onto the mitochondrial membrane rather than its subcellular localization.