scholarly journals SURO-2/TMEM39 Facilitates Collagen Secretion through the Formation of Large COPII Vesicles

2020 ◽  
Author(s):  
Kiho Lee ◽  
Jee Young Sung ◽  
Saerom Lee ◽  
Gaeun Lim ◽  
Kyung Jin Jung ◽  
...  
Keyword(s):  
Critical Factor ◽  
C Elegans ◽  
Golgi Transport ◽  
Collagen Secretion ◽  
Transport Vesicles ◽  
Transmission Electron ◽  
Copii Vesicle ◽  
Copii Vesicles ◽  
General Transport ◽  
Cuticle Thickness

Abstract Fibrosis of various tissues is a typical disease caused by excessive production and secretion of extracellular matrix. We used Caenorhabditis elegans to investigate the formation of large transport vesicles to understand collagen secretion, a critical factor in fibrosis formation. The suro-2 mutant displays obvious defects in collagen secretion and cuticle structure including a rupture phenotype in early adults. Transmission electron microscopy exhibited that the cuticle thickness of the suro-2 mutant was severely reduced. SURO-2/TMEM39 has 8 transmembrane domains and localizes in the endoplasmic reticulum (ER) membrane. SURO-2 interacts directly with NPP-20/Sec13, a component of the coat protein II (COPII) complex responsible for ER-to-Golgi transport. SURO-2 and NPP-20 localized at the same large puncta, a large COPII vesicle enough to accommodate collagens. We report here that SURO-2/TMEM39 is highly conserved among animal species and is a specialized regulator of bulky collagen secretion rather than general transport in C. elegans.

scholarly journals Erv14p Directs a Transmembrane Secretory Protein into COPII-coated Transport Vesicles

2002 ◽  
Vol 13 (3) ◽  
pp. 880-891 ◽  
Author(s):  
Jacqueline Powers ◽  
Charles Barlowe
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Pathway ◽  
Integral Membrane Protein ◽  
Secretory Protein ◽  
Conserved Residues ◽  
Early Secretory Pathway ◽  
Transport Vesicles ◽  
Copii Vesicle ◽  
Copii Vesicles ◽  
Selection Of

Erv14p is a conserved integral membrane protein that traffics in COPII-coated vesicles and localizes to the early secretory pathway in yeast. Deletion of ERV14 causes a defect in polarized growth because Axl2p, a transmembrane secretory protein, accumulates in the endoplasmic reticulum and is not delivered to its site of function on the cell surface. Herein, we show that Erv14p is required for selection of Axl2p into COPII vesicles and for efficient formation of these vesicles. Erv14p binds to subunits of the COPII coat and binding depends on conserved residues in a cytoplasmically exposed loop domain of Erv14p. When mutations are introduced into this loop, an Erv14p-Axl2p complex accumulates in the endoplasmic reticulum, suggesting that Erv14p links Axl2p to the COPII coat. Based on these results and further genetic experiments, we propose Erv14p coordinates COPII vesicle formation with incorporation of specific secretory cargo.

scholarly journals Golgi Structure Correlates with Transitional Endoplasmic Reticulum Organization in Pichia pastoris and Saccharomyces cerevisiae

1999 ◽  
Vol 145 (1) ◽  
pp. 69-81 ◽  
Author(s):  
Olivia W. Rossanese ◽  
Jon Soderholm ◽  
Brooke J. Bevis ◽  
Irina B. Sears ◽  
James O'Connor ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Pichia Pastoris ◽  
Fluorescent Protein ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis ◽  
Coat Proteins ◽  
Transport Vesicles ◽  
Copii Vesicle ◽  
Copii Vesicles ◽  
Green Fluorescent

Golgi stacks are often located near sites of “transitional ER” (tER), where COPII transport vesicles are produced. This juxtaposition may indicate that Golgi cisternae form at tER sites. To explore this idea, we examined two budding yeasts: Pichia pastoris, which has coherent Golgi stacks, and Saccharomyces cerevisiae, which has a dispersed Golgi. tER structures in the two yeasts were visualized using fusions between green fluorescent protein and COPII coat proteins. We also determined the localization of Sec12p, an ER membrane protein that initiates the COPII vesicle assembly pathway. In P. pastoris, Golgi stacks are adjacent to discrete tER sites that contain COPII coat proteins as well as Sec12p. This arrangement of the tER-Golgi system is independent of microtubules. In S. cerevisiae, COPII vesicles appear to be present throughout the cytoplasm and Sec12p is distributed throughout the ER, indicating that COPII vesicles bud from the entire ER network. We propose that P. pastoris has discrete tER sites and therefore generates coherent Golgi stacks, whereas S. cerevisiae has a delocalized tER and therefore generates a dispersed Golgi. These findings open the way for a molecular genetic analysis of tER sites.

scholarly journals Genes that control the fidelity of endoplasmic reticulum to Golgi transport identified as suppressors of vesicle budding mutations.

1996 ◽  
Vol 7 (7) ◽  
pp. 1043-1058 ◽  
Author(s):  
M J Elrod-Erickson ◽  
C A Kaiser
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Integral Membrane Proteins ◽  
Secretory Proteins ◽  
Vesicle Formation ◽  
Gene Products ◽  
Vesicle Budding ◽  
Golgi Transport ◽  
Transport Vesicles ◽  
Copii Vesicle

Although convergent evidence suggests that proteins destined for export from the endoplasmic reticulum (ER) are separated from resident ER proteins and are concentrated into transport vesicles, the proteins that regulate this process have remained largely unknown. In a screen for suppressors of mutations in the essential COPII gene SEC13, we identified three genes (BST1, BST2/EMP24, and BST3) that negatively regulate COPII vesicle formation, preventing the production of vesicles with defective or missing subunits. Mutations in these genes slow the secretion of some secretory proteins and cause the resident ER proteins Kar2p and Pdi1p to leak more rapidly from the ER, indicating that these genes are also required for proper discrimination between resident ER proteins and Golgi-bound cargo molecules. The BST1 and BST2/EMP24 genes code for integral membrane proteins that reside predominantly in the ER. Our data suggest that the BST gene products represent a novel class of ER proteins that link the regulation of vesicle coat assembly to cargo sorting.

scholarly journals Reconstitution of COPII vesicle fusion to generate a pre-Golgi intermediate compartment

2004 ◽  
Vol 167 (6) ◽  
pp. 997-1003 ◽  
Author(s):  
Dalu Xu ◽  
Jesse C. Hay
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Fusion ◽  
Secretory Pathway ◽  
Golgi Stack ◽  
Golgi Membranes ◽  
Transport Vesicles ◽  
Copii Vesicle ◽  
Intermediate Compartment ◽  
Copii Vesicles

What is the first membrane fusion step in the secretory pathway? In mammals, transport vesicles coated with coat complex (COP) II deliver secretory cargo to vesicular tubular clusters (VTCs) that ferry cargo from endoplasmic reticulum exit sites to the Golgi stack. However, the precise origin of VTCs and the membrane fusion step(s) involved have remained experimentally intractable. Here, we document in vitro direct tethering and SNARE-dependent fusion of endoplasmic reticulum–derived COPII transport vesicles to form larger cargo containers. The assembly did not require detectable Golgi membranes, preexisting VTCs, or COPI function. Therefore, COPII vesicles appear to contain all of the machinery to initiate VTC biogenesis via homotypic fusion. However, COPI function enhanced VTC assembly, and early VTCs acquired specific Golgi components by heterotypic fusion with Golgi-derived COPI vesicles.

scholarly journals Proteomic Profiling of Mammalian COPII Vesicles

2018 ◽  
Author(s):  
Frank Adolf ◽  
Manuel Rhiel ◽  
Bernd Hessling ◽  
Andrea Hellwig ◽  
Felix T. Wieland
Keyword(s):  
Intracellular Transport ◽  
Spectrometric Analysis ◽  
Secretory Proteins ◽  
Proteomic Profiling ◽  
Vesicular Carriers ◽  
Copii Vesicle ◽  
Cargo Proteins ◽  
Core Proteome ◽  
Copii Vesicles

AbstractIntracellular transport and homeostasis of the endomembrane system in eukaryotic cells depend on formation and fusion of vesicular carriers. COPII vesicles export newly synthesized secretory proteins from the endoplasmic reticulum (ER). They are formed by sequential recruitment of the small GTP binding protein Sar1, the inner coat complex Sec23/24, and the outer coat complex Sec13/31. In order to investigate the roles of mammalian Sec24 isoforms in cargo sorting, we have combined in vitro COPII vesicle reconstitutions with SILAC-based mass spectrometric analysis. This approach enabled us to identify the core proteome of mammalian COPII vesicles. Comparison of the proteomes generated from vesicles with different Sec24 isoforms confirms several established isoform-dependent cargo proteins, and identifies ERGIC1 and CNIH1 as novel Sec24C‐ and Sec24A-specific cargo proteins, respectively. Proteomic analysis of vesicles reconstituted with a Sec24C mutant, bearing a compromised binding site for the ER-to-Golgi QSNARE Syntaxin5, revealed that the SM/Munc18 protein SCFD1 binds to Syntaxin5 prior to its sorting into COPII vesicles. Furthermore, analysis of Sec24D mutants implicated in the development of a syndromic form of osteogenesis imperfecta showed sorting defects for the three ER-to-Golgi QSNAREs Syntaxin5, GS27, and Bet1.

scholarly journals Vesicular and uncoated Rab1-dependent cargo carriers facilitate ER to Golgi transport

2020 ◽  
Vol 133 (14) ◽  
pp. jcs239814 ◽  
Author(s):  
Laura M. Westrate ◽  
Melissa J. Hoyer ◽  
Michael J. Nash ◽  
Gia K. Voeltz
Keyword(s):  
Endoplasmic Reticulum ◽  
De Novo ◽  
Coated Vesicle ◽  
First Person ◽  
Coat Proteins ◽  
Animal Cells ◽  
Golgi Transport ◽  
Er Exit Sites ◽  
Copii Vesicles ◽  
Export System

ABSTRACTSecretory cargo is recognized, concentrated and trafficked from endoplasmic reticulum (ER) exit sites (ERES) to the Golgi. Cargo export from the ER begins when a series of highly conserved COPII coat proteins accumulate at the ER and regulate the formation of cargo-loaded COPII vesicles. In animal cells, capturing live de novo cargo trafficking past this point is challenging; it has been difficult to discriminate whether cargo is trafficked to the Golgi in a COPII-coated vesicle. Here, we describe a recently developed live-cell cargo export system that can be synchronously released from ERES to illustrate de novo trafficking in animal cells. We found that components of the COPII coat remain associated with the ERES while cargo is extruded into COPII-uncoated, non-ER associated, Rab1 (herein referring to Rab1a or Rab1b)-dependent carriers. Our data suggest that, in animal cells, COPII coat components remain stably associated with the ER at exit sites to generate a specialized compartment, but once cargo is sorted and organized, Rab1 labels these export carriers and facilitates efficient forward trafficking.This article has an associated First Person interview with the first author of the paper.

scholarly journals New Al-Ni-Ge Contacts on GaAs; Their Structure and Electrical Properties

1988 ◽  
Vol 126 ◽  
Author(s):  
Z. Liliental-Weber ◽  
J. Washburn ◽  
C. Musgrave ◽  
E. R. Weber ◽  
R. Zuleeg ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Electrical Contact ◽  
Critical Factor ◽  
Contact Layer ◽  
Auger Spectroscopy ◽  
Semiconductor Surface ◽  
Chemical Cleaning ◽  
Tunneling Mechanism ◽  
Transmission Electron ◽  
Secondary Ion

ABSTRACTThe structure and composition of the recently developed Al-Ni-Ge ohmic contacts to n-GaAs were investigated by transmission electron microscopy combined with secondary ion mass spectroscopy (SIMS) and Auger spectroscopy. The semiconductor/metal-alloy interface of these contacts remain very flat after annealing (500°C, for 1 min - contact resistance 1.4×10−6Ωcm2), in contrast to the widely used Au-Ni-Ge contacts. The metal sequence during deposition is found to be a critical factor in determining the electrical contact properties and the dispersion of the oxide layer on the semiconductor surface after chemical cleaning. Ge doping of the GaAs beneath the contact layer was observed by SIMS, and a tunneling mechanism through the n+GaAs:Ge layer was proposed to explain the ohmic properties of the contacts.

The ultrastructure of the cuticle and sheath of infective juveniles of entomopathogenic steinernematid nematodes

1998 ◽  
Vol 72 (3) ◽  
pp. 257-266 ◽  
Author(s):  
M.N. Patel ◽  
D.J. Wright
Keyword(s):  
Electron Microscopy ◽  
Steinernema Carpocapsae ◽  
The Other ◽  
Fluid Content ◽  
Transmission Electron ◽  
New Material ◽  
Per Se ◽  
Cuticle Thickness ◽  
Substantial Change ◽  
Median Layer

AbstractThe ultrastructure of the cuticle of infective juveniles (IJs) of Steinernema carpocapsae (newly emerged and 80-day-old) and newly emerged IJs of S. riobravis, S. feltiae and S. glaseri was examined using transmission electron microscopy. The thickness of four distinctive layers of the cuticle was measured: epicuticle, cortical and median layer, striated layer and fibrous mat. The thickness of the cuticle was correlated with the size of the IJ. In the case of newly emerged IJs, the smallest species, S. carpocapsae, had a cuticle thickness of c. 270 nm compared with c. 460 nm for S. glaseri, the largest of the four species. The overall thickness of the cuticle or the thickness of the cuticle layers was not correlated with the ability of the IJs of the four species to survive desiccation per se. The major difference between newly emerged IJs of the four species was that S. carpocapsae had a proportionately thicker striated layer compared with the other three species. The significance of this is not known but it may be an adaptation involving the nictation behaviour of this species. A substantial change was observed in the cuticle of aged (80-day-old) IJs of S. carpocapsae, whereby the thickness of the cortical and median layer increased by more than 100% and the overall thickness of the cuticle increased by about 50%. Two possible explanations for this increase are: (i) new material was synthesized; or (ii) the fluid content of this layer increased due to an increase in the permeability of the outer layers of the cuticle. The ultrastructure of the sheaths of S. feltiae and S. glaseri was also examined and, apart from S. glaseri having a thicker sheath, the structure of the sheath in both species was similar, with the epicuticle and striated layer still visible.

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