Alternative Start Codon Connects eIF5A to Mitochondria
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- 作者：Karina Danielle Pereira ; Letí ; cia Tamborlin ; Letí ; cia Meneguello ; André ; Ricardo Gomes de Proenç ; a ; Isadora Cristina de Paula Andrade Almeida ; Rogé ; rio Ferreira Lourenç ; o and Augusto Ducati Luchessi
- 刊名：Journal of Cellular Physiology
- 出版年：2016
- 出版时间：December 2016
- 年：2016
- 卷：231
- 期：12
- 页码：2682-2689
- 全文大小：1243K
- ISSN：1097-4652
文摘
Eukaryotic translation initiation factor 5A (eIF5A), a protein containing the amino acid residue hypusine required for its activity, is involved in a number of physiological and pathological cellular processes. In humans, several EIF5A1 transcript variants encode the canonical eIF5A1 isoform B, whereas the hitherto uncharacterized variant A is expected to code for a hypothetical eIF5A1 isoform, referred to as isoform A, which has an additional N-terminal extension. Herein, we validate the existence of eIF5A1 isoform A and its production from transcript variant A. In fact, variant A was shown to encode both eIF5A1 isoforms A and B. Mutagenic assays revealed different efficiencies in the start codons present in variant A, contributing to the production of isoform B at higher levels than isoform A. Immunoblotting and mass spectrometric analyses showed that isoform A can undergo hypusination and acetylation at specific lysine residues, as observed for isoform B. Examination of the N-terminal extension suggested that it might confer mitochondrial targeting. Correspondingly, we found that isoform A, but not isoform B, co-purified with mitochondria when the proteins were overproduced. These findings suggest that eIF5A1 isoform A has a role in mitochondrial function. J. Cell. Physiol. 231: 2682–2689, 2016.