scholarly journals A molecular specificity code for the three mammalian KDEL receptors

2007 ◽  
Vol 179 (6) ◽  
pp. 1193-1204 ◽  
Author(s):  
Irina Raykhel ◽  
Heli Alanen ◽  
Kirsi Salo ◽  
Jaana Jurvansuu ◽  
Van Dat Nguyen ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Coat Protein ◽  
Bimolecular Fluorescence Complementation ◽  
Reporter Construct ◽  
Human Proteins ◽  
Molecular Specificity ◽  
Intermediate Compartment ◽  
Kdel Receptor ◽  
Dependent Pathway ◽  
Construct System

AC-terminal KDEL-like motif prevents secretion of soluble endoplasmic reticulum (ER)–resident proteins. This motif interacts with KDEL receptors localized in the intermediate compartment and Golgi apparatus. Such binding triggers retrieval back to the ER via a coat protein I–dependent pathway. To date, two human KDEL receptors have been reported. Here, we report the Golgi localization of a third human KDEL receptor. Using a reporter construct system from a screen of 152 variants, we identified 35 KDEL-like variants that result in efficient ER localization but do not match the current Prosite motif for ER localization ([KRHQSA]-[DENQ]-E-L). We cloned 16 human proteins with one of these motifs and all were found in the ER. A subsequent screen by bimolecular fluorescence complementation determined the specificities of the three human KDEL receptors. Each KDEL receptor has a unique pattern of motifs with which it interacts. This suggests a specificity in the retrieval of human proteins that contain different KDEL variants.

scholarly journals TFG facilitates outer coat disassembly on COPII transport carriers to promote tethering and fusion with ER–Golgi intermediate compartments

2017 ◽  
Vol 114 (37) ◽  
pp. E7707-E7716 ◽  
Author(s):  
Michael G. Hanna ◽  
Samuel Block ◽  
E. B. Frankel ◽  
Feng Hou ◽  
Adam Johnson ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Coat Protein ◽  
Protein Trafficking ◽  
Secretory Protein ◽  
Dependent Manner ◽  
Outer Coat ◽  
Concentration Dependent Manner ◽  
C Terminus ◽  
Intermediate Compartment ◽  
Fused Gene

The conserved coat protein complex II (COPII) mediates the initial steps of secretory protein trafficking by assembling onto subdomains of the endoplasmic reticulum (ER) in two layers to generate cargo-laden transport carriers that ultimately fuse with an adjacent ER–Golgi intermediate compartment (ERGIC). Here, we demonstrate that Trk-fused gene (TFG) binds directly to the inner layer of the COPII coat. Specifically, the TFG C terminus interacts with Sec23 through a shared interface with the outer COPII coat and the cargo receptor Tango1/cTAGE5. Our findings indicate that TFG binding to Sec23 outcompetes these other associations in a concentration-dependent manner and ultimately promotes outer coat dissociation. Additionally, we demonstrate that TFG tethers vesicles harboring the inner COPII coat, which contributes to their clustering between the ER and ERGIC in cells. Together, our studies define a mechanism by which COPII transport carriers are retained locally at the ER/ERGIC interface after outer coat disassembly, which is a prerequisite for fusion with ERGIC membranes.

scholarly journals The Mammalian Protein (rbet1) Homologous to Yeast Bet1p Is Primarily Associated with the Pre-Golgi Intermediate Compartment and Is Involved in Vesicular Transport from the Endoplasmic Reticulum to the Golgi Apparatus

1997 ◽  
Vol 139 (5) ◽  
pp. 1157-1168 ◽  
Author(s):  
Tao Zhang ◽  
Siew Heng Wong ◽  
Bor Luen Tang ◽  
Yue Xu ◽  
Frank Peter ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
G Protein ◽  
Vesicular Transport ◽  
Dependent Manner ◽  
Golgi Transport ◽  
Golgi Region ◽  
Intermediate Compartment ◽  
Kdel Receptor ◽  
Mammalian Protein

Yeast Bet1p participates in vesicular transport from the endoplasmic reticulum to the Golgi apparatus and functions as a soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) associated with ER-derived vesicles. A mammalian protein (rbet1) homologous to Bet1p was recently identified, and it was concluded that rbet1 is associated with the Golgi apparatus based on the subcellular localization of transiently expressed epitope-tagged rbet1. In the present study using rabbit antibodies raised against the cytoplasmic domain of rbet1, we found that the majority of rbet1 is not associated with the Golgi apparatus as marked by the Golgi mannosidase II in normal rat kidney cells. Rather, rbet1 is predominantly associated with vesicular spotty structures that concentrate in the peri-Golgi region but are also present throughout the cytoplasm. These structures colocalize with the KDEL receptor and ERGIC-53, which are known to be enriched in the intermediate compartment. When the Golgi apparatus is fragmented by nocodazole treatment, a significant portion of rbet1 is not colocalized with structures marked by Golgi mannosidase II or the KDEL receptor. Association of rbet1 in cytoplasmic spotty structures is apparently not altered by preincubation of cells at 15°C. However, upon warming up from 15 to 37°C, rbet1 concentrates into the peri-Golgi region. Furthermore, rbet1 colocalizes with vesicular stomatitis virus G-protein en route from the ER to the Golgi. Antibodies against rbet1 inhibit in vitro transport of G-protein from the ER to the Golgi apparatus in a dose-dependent manner. This inhibition can be neutralized by preincubation of antibodies with recombinant rbet1. EGTA is known to inhibit ER-Golgi transport at a stage after vesicle docking but before the actual fusion event. Antibodies against rbet1 inhibit ER-Golgi transport only when they are added before the EGTA-sensitive stage. These results suggest that rbet1 may be involved in the docking process of ER- derived vesicles with the cis-Golgi membrane.

N-Ac-KDEL induces rapid alterations in endoplasmic reticulum structure

1991 ◽  
Vol 49 ◽  
pp. 260-261
Author(s):  
Stephen M. Wolniak ◽  
Paul M. Larsen ◽  
Eliot M. Herm
Keyword(s):  
Endoplasmic Reticulum ◽  
Living Cells ◽  
Carboxy Terminus ◽  
Specific Receptor ◽  
Intermediate Compartment ◽  
Endoplasmic Reticulum Structure ◽  
Kdel Receptor

KDEL (i.e., Lysine-Aspartate-Glutamate-Leucine) is a tetrapeptide motif that serves as a retention sequence at the carboxy-terminus of proteins which reside within the ER lumen. A specific receptor located in or near the cis-Golgi recognizes proteins bearing carboxyterminal KDEL and mediates their return to the ER. We reasoned that it may be possible to saturate the KDEL receptor with a hapten, thereby competitively inhibiting its function in living cells. We hypothesized that if we blinded the receptor with an excess of hapten then the intermediate compartment should be unable to differentiate between polypeptides containing carboxyterminal KDEL from those that do not. If the receptor could be blinded, then KDEL-polypeptides such as BiP should be secreted.

scholarly journals The ULK1-FBXW5-SEC23B nexus controls autophagy

2018 ◽  
Author(s):  
Yeon-Tae Jeong ◽  
Daniele Simoneschi ◽  
Sarah Keegan ◽  
David Melville ◽  
Natalia S. Adler ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Coat Protein ◽  
Protein Complex ◽  
Secretory Pathway ◽  
Molecular Mechanisms ◽  
Proteasomal Degradation ◽  
Nutrient Deprivation ◽  
Autophagic Flux ◽  
Intermediate Compartment ◽  
F Box Protein

ABSTRACTIn response to nutrient deprivation, the cell needs to mobilize an extensive amount of membrane to form and grow the autophagosome, allowing the progression of autophagy. By providing membranes and a source for LC3 lipidation, COPII (Coat Protein Complex II) localizes to the endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC) and promotes autophagosome biogenesis. However, the molecular mechanisms that, in response to starvation, divert COPII from the secretory pathway to the autophagic pathway are largely unknown. Here, we show that the F-box protein FBXW5 targets SEC23B, a component of COPII, for proteasomal degradation and that this event limits the autophagic flux in the presence of nutrients. In response to starvation, ULK1 phosphorylates SEC23B on Serine 186, preventing the interaction of SEC23B with FBXW5 and, therefore, inhibiting its degradation. Phosphorylated and stabilized SEC23B associates with SEC24A and SEC24B, but not SEC24C and SEC24D, and they re-localize to the ERGIC, promoting autophagic flux. Induction of autophagy and localization of both SEC23B and SEC24B to the ERGIC in response to nutrient deprivation are significantly reduced in SEC23B(S186A) knock-in cells. We propose that, in the presence of nutrients, FBXW5 limits COPII-mediated autophagosome biogenesis. Inhibition of this event by ULK1 ensures efficient execution of the autophagic cascade in response to nutrient starvation.

scholarly journals KDEL Receptor (Erd2p)-mediated Retrograde Transport of the Cholera Toxin A Subunit from the Golgi Involves COPI, p23, and the COOH Terminus of Erd2p

1998 ◽  
Vol 143 (3) ◽  
pp. 601-612 ◽  
Author(s):  
Irina Majoul ◽  
Kai Sohn ◽  
Felix Theodor Wieland ◽  
Rainer Pepperkok ◽  
Mariagrazia Pizza ◽  
...  
Keyword(s):  
Coat Protein ◽  
Cholera Toxin ◽  
Retrograde Transport ◽  
Vero Cells ◽  
Toxin A ◽  
P24 Protein ◽  
A Subunit ◽  
Intermediate Compartment ◽  
Camp Levels ◽  
Kdel Receptor

A cholera toxin mutant (CTX–K63) unable to raise cAMP levels was used to study in Vero cells the retrograde transport of the toxin A subunit (CTX-A–K63), which possesses a COOH-terminal KDEL retrieval signal. Microinjected GTP-γ-S inhibits the internalization as well as Golgi–ER transport of CTX-A–K63. The appearance of CTX-A–K63 in the Golgi induces a marked dispersion of Erd2p and p53 but not of the Golgi marker giantin. Erd2p is translocated under these conditions most likely to the intermediate compartment as indicated by an increased colocalization of Erd2p with mSEC13, a member of the mammalian coat protein II complex. IgGs as well as Fab fragments directed against Erd2p, β-COP, or p23, a new member of the p24 protein family, inhibit or block retrograde transport of CTX-A–K63 from the Golgi without affecting its internalization or its transport to the Golgi. Anti-Erd2p antibodies do not affect the binding of CTX-A to Erd2p, but inhibit the CTX-K63–induced translocation of Erd2p and p53.

scholarly journals Prohibitin: A Novel Molecular Player in KDEL Receptor Signalling

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Monica Giannotta ◽  
Giorgia Fragassi ◽  
Antonio Tamburro ◽  
Capone Vanessa ◽  
Alberto Luini ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Membrane Trafficking ◽  
Transmembrane Domain ◽  
Cell Cycle Control ◽  
Retrograde Transport ◽  
Multifunctional Protein ◽  
G Protein Coupled ◽  
Kdel Receptor ◽  
Prohibitin 1

The KDEL receptor (KDELR) is a seven-transmembrane-domain protein involved in retrograde transport of protein chaperones from the Golgi complex to the endoplasmic reticulum. Our recent findings have shown that the Golgi-localised KDELR acts as a functional G-protein-coupled receptor by binding to and activating Gs and Gq. These G proteins induce activation of PKA and Src and regulate retrograde and anterograde Golgi trafficking. Here we used an integrated coimmunoprecipitation and mass spectrometry approach to identify prohibitin-1 (PHB) as a KDELR interactor. PHB is a multifunctional protein that is involved in signal transduction, cell-cycle control, and stabilisation of mitochondrial proteins. We provide evidence that depletion of PHB induces intense membrane-trafficking activity at the ER–Golgi interface, as revealed by formation of GM130-positive Golgi tubules, and recruitment of p115,β-COP, and GBF1 to the Golgi complex. There is also massive recruitment of SEC31 to endoplasmic-reticulum exit sites. Furthermore, absence of PHB decreases the levels of the Golgi-localised KDELR, thus preventing KDELR-dependent activation of Golgi-Src and inhibiting Golgi-to-plasma-membrane transport of VSVG. We propose a model whereby in analogy to previous findings (e.g., the RAS-RAF signalling pathway), PHB can act as a signalling scaffold protein to assist in KDELR-dependent Src activation.

Selective Accumulation of the Endoplasmic Reticulum–Golgi Intermediate Compartment Induced by the Antitumor Drug KRN5500

2000 ◽  
Vol 256 (2) ◽  
pp. 468-479 ◽  
Author(s):  
Masaru Kamishohara ◽  
Susan Kenney ◽  
Renee Domergue ◽  
David T. Vistica ◽  
Edward A. Sausville
Keyword(s):  
Endoplasmic Reticulum ◽  
Antitumor Drug ◽  
Intermediate Compartment ◽  
Selective Accumulation
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