Phosphorylation of Y14 Modulates Its Interaction with Proteins Involved in mRNA Metabolism and Influences Its Methylation

• Published in: The Journal of biological chemistry Vol. 280; no. 41; pp. 34507 - 34512
• Main Authors: Hsu, Ia-Wen, Hsu, Min, Li, Chin, Chuang, Tzu-Wei, Lin, Ru-Inn, Tarn, Woan-Yuh
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 14.10.2005; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; Animals; Arginine - chemistry; Exons; Glutathione Transferase - metabolism; HeLa Cells; Humans; Introns; Methylation; Models, Biological; Models, Genetic; Molecular Sequence Data; Mutation; Oocytes - metabolism; Peptides - chemistry; Phosphorylation; Plasmids - metabolism; Protein Binding; Protein Structure, Tertiary; Recombinant Proteins - chemistry; RNA - chemistry; RNA Splicing; RNA, Messenger - metabolism; RNA-Binding Proteins - chemistry; RNA-Binding Proteins - metabolism; Transfection; Xenopus laevis
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M507658200

The multicomponent exon junction complex (EJC) is deposited on the spliced mRNA during pre-mRNA splicing and is implicated in several post-splicing events, including mRNA export, nonsense-mediated mRNA decay (NMD), and translation control. This report is the first to identify potential post-translational modifications of the EJC core component Y14. We demonstrate that Y14 is phosphorylated at its repeated arginine/serine (RS) dipeptides, likely by SR protein-specific kinases. Phosphorylation of Y14 abolished its interaction with EJC components as well as factors that function downstream of the EJC. A non-phosphorylatable Y14 mutant was equivalent to the wild-type protein with respect to its association with spliced mRNA and its ability in NMD activation, but the mutant sequestered EJC and NMD factors on ribosome-containing mRNA ribonucleoproteins (mRNPs). We therefore hypothesize that phosphorylation of Y14 occurs upon completion of mRNA surveillance, leading to dissociation of Y14 from ribosome-containing mRNPs. Moreover, we found that Y14 is possibly methylated at multiple arginine residues in the carboxyl-terminal domain and that methylation of Y14 was antagonized by phosphorylation of RS dipeptides. This study reveals antagonistic post-translational modifications of Y14 that may be involved in the remodeling of Y14-containing mRNPs.