Single translation—dual destination: mechanisms of dual protein targeting in eukaryotes

Abstract

It is well documented that single eukaryotic genes can give rise to proteins that are localized to several subcellular locations. This is achieved at the level of transcription, splicing and translation, and results in two or more translation products that either harbour or lack specific targeting signals. Nevertheless, the possibility of dual targeting of a single translation product has recently emerged. Here, we review cases of such dual targeting with emphasis on the mechanisms through which these phenomena occur. Proteins that harbour one signal, two separate signals or an overlapping ambiguous signal may follow dual distribution in the cell. The mechanism of dual targeting is driven by the competition or promiscuity of various molecular events. Protein folding, post-translational modification and proteinprotein interaction are key players in this phenomenon.

One Single In-frame AUG Codon Is Responsible for a Diversity of Subcellular Localizations of Glutaredoxin 2 in Saccharomyces cerevisiae

“…5B. Multiple strategies for the localization of proteins in more than one subcellular compartment in eukaryotic cells have been established (26,29). Among the different possible mechanisms, S. cerevisiae Grx2 constitutes a unique case in that it cannot be included into one single group of proteins.…”

“…A major aspect of the understanding of protein functions in eukaryotic cells is represented by the analysis of the mechanisms by which proteins are targeted and distributed to their subcellular localizations (26). Most mitochondrial proteins are encoded by nuclear DNA and are processed by a specific machinery ("translocases") consisting of several sets of proteins, whose functions involve specific binding, translocation, maturation, and membrane insertion (27).…”

Protein Disulfide Isomerase-2 of Arabidopsis Mediates Protein Folding and Localizes to Both the Secretory Pathway and Nucleus, Where It Interacts with Maternal Effect Embryo Arrest Factor

“…Post-translational insertion of the signal peptide-containing polypeptide was observed in a few cases in animals, yeast and plants (Cramer et al, 1987;Plath et al, 1998;Rapoport et al, 1999). Alternatively, PDI2 could enter the nucleus by interacting with MEE8, which has a strong NLS ( Table 2) that can mask the signal peptide (Karniely and Pines, 2005).…”

Plant organellar protein targeting: a traffic plan still under construction

“…The targeting properties of a protein are dramatically influenced by cellular conditions (reviewed in [34]). In the case of catalase A (Cta1p) in yeast, an important H 2 O 2 scavenger, the protein contains peroxisome targeting signals at both the carboxy end and within the N-terminal third of the protein, and no clearly recognizable mitochondrial presequence.…”

“…What has emerged from these experiments suggests a trend in post-endosymbiotic gene evolution towards protein versatility by multi-targeting. However, given the responsiveness of protein targeting behavior to cellular conditions [34], such targeting assay procedures cannot substitute for high-resolution subcellular fractionation to localize proteins accurately. …”