title: Cellular growth defects triggered by an overload of protein localization processes.
abstract: High-level expression of a protein localized to an intracellular compartment is expected to cause cellular defects because it overloads localization processes. However, overloads of localization processes have never been studied systematically. Here, we show that the expression levels of green fluorescent proteins (GFPs) with localization signals were limited to the same degree as a toxic misfolded GFP in budding yeast cells, and that their high-level expression caused cellular defects associated with localization processes. We further show that limitation of the exportin Crm1 determined the expression limit of GFP with a nuclear export signal. Although misfolding of GFP with a vesicle-mediated transport signal triggered endoplasmic reticulum stress, it was not the primary determinant of its expression limit. The precursor of GFP with a mitochondrial targeting signal caused a cellular defect. Finally, we estimated the residual capacities of localization processes. High-level expression of a localized protein thus causes cellular defects by overloading the capacities of localization processes.
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Kintaka
authors.affiliation: Research Core for Interdisciplinary Sciences, Okayama University, Okayama, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Makanae
authors.affiliation: Research Core for Interdisciplinary Sciences, Okayama University, Okayama, Japan.
authors.forename: Hisao
authors.initials: H
authors.lastname: Moriya
mesh_terms: D049452:Green Fluorescent Proteins / Q000235:genetics; D028884:Karyopherins / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D000097606:Exportin 1 Protein
chemical_list: D049452:Green Fluorescent Proteins; D028884:Karyopherins; D018160:Receptors, Cytoplasmic and Nuclear; D000097606:Exportin 1 Protein