The Tobacco Luminal Binding Protein Is Encoded by a Multigene Family

Denecke, Jürgen; Goldman, Maria Helena S.; Demolder, Jan; Seurinck, Jef; Botterman, Johan

doi:10.2307/3869163

Cited by 88 publications

(173 citation statements)

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“…BiP appears to be ubiquitous in all eukaryotic cells and was recently identified within the ER ofwheat endosperm cells (7). Analyses of BiP cloned from several plant species confirmed that the plant proteins also contain the HDEL signal and that this signal functions in the retention ofproteins within the ER (3,4,9,17). Although under normal conditions of BiP expression this protein was shown to retain entirely within the ER, one can still argue that some BiP may escape retention and transport via the Golgi because the HDEL retention signal is known to be saturated (21).…”

Section: Discussionmentioning

confidence: 94%

Evidence for the Presence of Two Different Types of Protein Bodies in Wheat Endosperm

Rubin

Levanony²,

Galili³

1992

Plant Physiol.

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Storage proteins of wheat grains (Triticum L. em Thell) are deposited in protein bodies inside vacuoles. However, the subcellular sites and mechanisms of their aggregation into protein bodies are not clear. In the present report, we provide evidence for two different types of protein bodies, low-and high-density types that accumulate concurrently and independently in developing wheat endosperm cells. Gliadins were present in both types of protein bodies, whereas the high molecular weight glutenins were localized mainly in the dense ones. Pulse-chase experiments verified that the dense protein bodies were not formed by a gradual increase in density but, presumably, by a distinct, quick process of storage protein aggregation. Subcellular fractionation and electron microscopy studies revealed that the wheat homolog of immunoglobulin heavy-chain-binding protein, an endoplasmic reticulum-resident protein, was present within the dense protein bodies, implying that these were formed by aggregation of storage proteins within the endoplasmic reticulum. The present results suggest that a large part of wheat storage proteins aggregate into protein bodies within the rough endoplasmic reticulum. Because these protein bodies are too large to enter the Golgi, they are likely to be transported directly to vacuoles. This route may operate in concert with the known Golgi-mediated transport to vacuoles in which the storage proteins apparently condense into protein bodies at a postendoplasmic reticulum location. Our results further suggest that although gliadins are transported by either one of these routes, the high molecular weight glutenins use only the Golgi bypass route.

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Section: Discussionmentioning

confidence: 94%

Evidence for the Presence of Two Different Types of Protein Bodies in Wheat Endosperm

Rubin

Levanony²,

Galili³

1992

Plant Physiol.

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“…The level of endogenous BiP protein was not elevated more than 20-40% when it was induced by BiP inducer X (BIX) (20). A discrepancy between overexpressed BiP mRNA and BiP protein levels was also reported in Saccaharomyces cerevisiae (30). In this respect, BiP behaves very differently than other ER proteins, such as calreticulin, which can be overexpressed 50-to 100-fold without a divergence between protein and mRNA levels.…”

Section: Discussionmentioning

confidence: 97%

Restoration of visual function in P23H rhodopsin transgenic rats by gene delivery of BiP/Grp78

Gorbatyuk¹,

Knox²,

LaVail

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

248

272

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The P23H mutation within the rhodopsin gene (RHO) causes rhodopsin misfolding, endoplasmic reticulum (ER) stress, and activates the unfolded protein response (UPR), leading to rod photoreceptor degeneration and autosomal dominant retinitis pigmentosa (ADRP). Grp78/BiP is an ER-localized chaperone that is induced by UPR signaling in response to ER stress. We have previously demonstrated that BiP mRNA levels are selectively reduced in animal models of ADRP arising from P23H rhodopsin expression at ages that precede photoreceptor degeneration. We have now overexpressed BiP to test the hypothesis that this chaperone promotes the trafficking of P23H rhodopsin to the cell membrane, reprograms the UPR favoring the survival of photoreceptors, blocks apoptosis, and, ultimately, preserves vision in ADRP rats. In cell culture, increasing levels of BiP had no impact on the localization of P23H rhodopsin. However, BiP overexpression alleviated ER stress by reducing levels of cleaved pATF6 protein, phosphorylated eIF2α and the proapoptotic protein CHOP. In P23H rats, photoreceptor levels of cleaved ATF6, pEIF2α, CHOP, and caspase-7 were much higher than those of wild-type rats. Subretinal delivery of AAV5 expressing BiP to transgenic rats led to reduction in CHOP and photoreceptor apoptosis and to a sustained increase in electroretinogram amplitudes. We detected complexes between BiP, caspase-12, and the BH3-only protein BiK that may contribute to the antiapoptotic activity of BiP. Thus, the preservation of photoreceptor function resulting from elevated levels of BiP is due to suppression of apoptosis rather than to a promotion of rhodopsin folding.autosomal dominant retinitis pigmentosa | endoplasmic reticulum stress | adeno-associated virus | unfolded protein response

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“…As shown in Figure 5, most of the AtELP protein was recovered in the P55 fraction (pellet fractionated at 55,000g), with lesser amounts in both low-speed (P8 and P14) and high-speed (P125) pellet fractions. On the other hand, the marker proteins for ER (BiP, Denecke et al, 1991;AtSEC12, Bar-Peled and Raikhel, 1997), tonoplast (7-TIP, Gomez and Chrispeels, 1993), and PM (RD28, Daniels et al, 1994) were found mostly in the lower-speed pellet fractions (PI, P3, P8, P14). Thus, AtELP had a different fractionation pattern from these endomembrane markers, suggesting that it was not localized in these organelles.…”

Section: Atelp Is An Integral Membrane Protein Found In a Novel Compamentioning

confidence: 99%

Cloning and Subcellular Location of an Arabidopsis Receptor-Like Protein That Shares Common Features with Protein-Sorting Receptors of Eukaryotic Cells

1997

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Many receptors involved in clathrin-mediated protein transport through the endocytic and secretory pathways of yeast and animal cells share common features. They are all type I integral membrane proteins containing cysteine-rich lumenal domains and cytoplasmic tails with tyrosine-containing sorting signals. The cysteine-rich domains are thought to be involved in ligand binding, whereas the cytoplasmic tyrosine motifs interact with clathrin-associated adaptor proteins during protein sorting along these pathways. In addition, tyrosine-containing signals are required for the retention and recycling of some of these membrane proteins to the trans-Golgi network. Here we report the characterization of an approximately 80-kD epidermal growth factor receptor-like type I integral membrane protein containing all of these functional motifs from Arabidopsis thaliana (called AtELP for A. thaliana Epidermal growth factor receptor-Like Protein). Biochemical analysis indicates that AtELP is a membrane protein found at high levels in the roots of both monocots and dicots. Subcellular fractionation studies indicate that the AtELP protein is present in two membrane fractions corresponding to a novel, undefined compartment and a fraction enriched in vesicles containing clathrin and its associated adaptor proteins. AtELP may therefore serve as a marker for compartments involved in intracellular protein trafficking in the plant cell.

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The Tobacco Luminal Binding Protein Is Encoded by a Multigene Family

Cited by 88 publications

References 0 publications

Evidence for the Presence of Two Different Types of Protein Bodies in Wheat Endosperm

Evidence for the Presence of Two Different Types of Protein Bodies in Wheat Endosperm

Restoration of visual function in P23H rhodopsin transgenic rats by gene delivery of BiP/Grp78

Cloning and Subcellular Location of an Arabidopsis Receptor-Like Protein That Shares Common Features with Protein-Sorting Receptors of Eukaryotic Cells

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