scholarly journals Distinct isoform-specific complexes of TANGO1 cooperatively facilitate collagen secretion from the endoplasmic reticulum

2016 ◽  
Vol 27 (17) ◽  
pp. 2688-2696 ◽  
Author(s):  
Miharu Maeda ◽  
Kota Saito ◽  
Toshiaki Katada
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Protein Complex ◽  
Integral Membrane Protein ◽  
Collagen Binding ◽  
Macromolecular Complexes ◽  
Collagen Secretion ◽  
Transport Vesicles ◽  
Er Exit Sites ◽  
Membrane Bound

Collagens synthesized within the endoplasmic reticulum (ER) are too large to fit in conventional COPII-coated transport vesicles; thus their export from the ER requires specialized factors. TANGO1 (L) is an integral membrane protein that binds to collagen and the coatomer of vesicles and is necessary for collagen secretion from the ER. Here we characterized the short isoform of TANGO1 (TANGO1S), lacking the collagen-binding domain, and found that it was independently required for collagen export from the ER. Moreover, we found that each of the TANGO1 isoforms forms a stable protein complex with factors involved in collagen secretion: TANGO1L/cTAGE5/Sec12 (900 kDa) and TANGO1S/cTAGE5/Sec12 (700 kDa). Of interest, TANGO1S and TANGO1L seemed to be interchangeable in exporting collagen from the ER. Our results suggest that mammalian ER exit sites possess two different-sized membrane-bound macromolecular complexes that specifically function in large-cargo export from the ER.

scholarly journals Erv26p Directs Pro-Alkaline Phosphatase into Endoplasmic Reticulum–derived Coat Protein Complex II Transport Vesicles

2006 ◽  
Vol 17 (11) ◽  
pp. 4780-4789 ◽  
Author(s):  
Catherine A. Bue ◽  
Christine M. Bentivoglio ◽  
Charles Barlowe
Keyword(s):  
Alkaline Phosphatase ◽  
Endoplasmic Reticulum ◽  
Coat Protein ◽  
Membrane Protein ◽  
Protein Complex ◽  
Integral Membrane Protein ◽  
Secretory Proteins ◽  
Complex Ii ◽  
Transport Vesicles ◽  
Copii Vesicles

Secretory proteins are exported from the endoplasmic reticulum (ER) in transport vesicles formed by the coat protein complex II (COPII). We detected Erv26p as an integral membrane protein that was efficiently packaged into COPII vesicles and cycled between the ER and Golgi compartments. The erv26Δ mutant displayed a selective secretory defect in which the pro-form of vacuolar alkaline phosphatase (pro-ALP) accumulated in the ER, whereas other secretory proteins were transported at wild-type rates. In vitro budding experiments demonstrated that Erv26p was directly required for packaging of pro-ALP into COPII vesicles. Moreover, Erv26p was detected in a specific complex with pro-ALP when immunoprecipitated from detergent-solublized ER membranes. Based on these observations, we propose that Erv26p serves as a transmembrane adaptor to link specific secretory cargo to the COPII coat. Because ALP is a type II integral membrane protein in yeast, these findings imply that an additional class of secretory cargo relies on adaptor proteins for efficient export from the ER.

scholarly journals Sequential Recruitment of the Endoplasmic Reticulum and Chloroplasts for Plant Potyvirus Replication

2009 ◽  
Vol 84 (2) ◽  
pp. 799-809 ◽  
Author(s):  
Taiyun Wei ◽  
Tyng-Shyan Huang ◽  
Jamie McNeil ◽  
Jean-François Laliberté ◽  
Jian Hong ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Integral Membrane Protein ◽  
Genome Replication ◽  
Transport Pathway ◽  
Er Exit Sites ◽  
Weight Protein ◽  
Infected Cells ◽  
Membrane Bound ◽  
Viral Replicase ◽  
Positive Strand Rna

ABSTRACT The replication of positive-strand RNA viruses occurs in cytoplasmic membrane-bound virus replication complexes (VRCs). Depending on the virus, distinct cellular organelles such as the endoplasmic reticulum (ER), chloroplast, mitochondrion, endosome, and peroxisome are recruited for the formation of VRC-associated membranous structures. Previously, the 6,000-molecular-weight protein (6K) of plant potyviruses was shown to be an integral membrane protein that induces the formation of 6K-containing membranous vesicles at endoplasmic reticulum (ER) exit sites for potyvirus genome replication. Here, we present evidence that the 6K-induced vesicles predominantly target chloroplasts, where they amalgamate and induce chloroplast membrane invaginations. The vesicular transport pathway and actomyosin motility system are involved in the trafficking of the 6K vesicles from the ER to chloroplasts. Viral RNA, double-stranded RNA, and viral replicase components are concentrated at the 6K vesicles that associate with chloroplasts in infected cells, suggesting that these chloroplast-bound 6K vesicles are the site for potyvirus replication. Taken together, these results suggest that plant potyviruses sequentially recruit the ER and chloroplasts for their genome replication.

scholarly journals TANGO1 recruits Sec16 to coordinately organize ER exit sites for efficient secretion

2017 ◽  
Vol 216 (6) ◽  
pp. 1731-1743 ◽  
Author(s):  
Miharu Maeda ◽  
Toshiaki Katada ◽  
Kota Saito
Keyword(s):  
Endoplasmic Reticulum ◽  
Direct Interaction ◽  
Macromolecular Complexes ◽  
Terminal Domain ◽  
Er Exit Sites ◽  
Membrane Bound ◽  
Collagen Receptor

Mammalian endoplasmic reticulum (ER) exit sites export a variety of cargo molecules including oversized cargoes such as collagens. However, the mechanisms of their assembly and organization are not fully understood. TANGO1L is characterized as a collagen receptor, but the function of TANGO1S remains to be investigated. Here, we show that direct interaction between both isoforms of TANGO1 and Sec16 is not only important for their correct localization but also critical for the organization of ER exit sites. The depletion of TANGO1 disassembles COPII components as well as membrane-bound ER-resident complexes, resulting in fewer functional ER exit sites and delayed secretion. The ectopically expressed TANGO1 C-terminal domain responsible for Sec16 binding in mitochondria is capable of recruiting Sec16 and other COPII components. Moreover, TANGO1 recruits membrane-bound macromolecular complexes consisting of cTAGE5 and Sec12 to the ER exit sites. These data suggest that mammalian ER exit sites are organized by TANGO1 acting as a scaffold, in cooperation with Sec16 for efficient secretion.

scholarly journals cTAGE5 mediates collagen secretion through interaction with TANGO1 at endoplasmic reticulum exit sites

2011 ◽  
Vol 22 (13) ◽  
pp. 2301-2308 ◽  
Author(s):  
Kota Saito ◽  
Koh Yamashiro ◽  
Yuki Ichikawa ◽  
Patrik Erlmann ◽  
Kenji Kontani ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Lymphoma ◽  
Coiled Coil ◽  
Integral Membrane Protein ◽  
Cutaneous T Cell Lymphoma ◽  
Rich Domain ◽  
Collagen Secretion ◽  
Er Exit Sites ◽  
Antigen 5 ◽  
Collagen Vii

Cutaneous T-cell lymphoma-–associated antigen 5 (cTAGE5), an originally identified tumor antigen, is overexpressed in various cancer cell lines. The cDNA encodes an integral membrane protein containing two coiled-coil motifs and a proline-rich domain. We show that cTAGE5 specifically localizes to the endoplasmic reticulum (ER) exit sites. In addition, cTAGE5 forms a complex with TANGO1 (MIA3), a previously characterized cargo receptor for collagen VII, by the interaction of their coiled-coil motifs. Of interest, cTAGE5, as well as TANGO1, is capable of interacting with the inner-layer coatomer of COPII Sec23/24 complex through their C-terminal proline-rich domains and required for collagen VII secretion. We propose that cTAGE5 acts as a coreceptor of TANGO1 for collagen VII export from the ER.

scholarly journals TANGO1 and SEC12 are copackaged with procollagen I to facilitate the generation of large COPII carriers

2018 ◽  
Vol 115 (52) ◽  
pp. E12255-E12264 ◽  
Author(s):  
Lin Yuan ◽  
Samuel J. Kenny ◽  
Juliet Hemmati ◽  
Ke Xu ◽  
Randy Schekman
Keyword(s):  
Endoplasmic Reticulum ◽  
Coat Protein ◽  
Protein Complex ◽  
Coated Vesicles ◽  
Initiation Factor ◽  
Interacting Protein ◽  
Complex Ii ◽  
Transport Vesicles ◽  
Er Exit Sites ◽  
Copii Vesicles

Large coat protein complex II (COPII)-coated vesicles serve to convey the large cargo procollagen I (PC1) from the endoplasmic reticulum (ER). The link between large cargo in the lumen of the ER and modulation of the COPII machinery remains unresolved. TANGO1 is required for PC secretion and interacts with PC and COPII on opposite sides of the ER membrane, but evidence suggests that TANGO1 is retained in the ER, and not included in normal size (<100 nm) COPII vesicles. Here we show that TANGO1 is exported out of the ER in large COPII-coated PC1 carriers, and retrieved back to the ER by the retrograde coat, COPI, mediated by the C-terminal RDEL retrieval sequence of HSP47. TANGO1 is known to target the COPII initiation factor SEC12 to ER exit sites through an interacting protein, cTAGE5. SEC12 is important for the growth of COPII vesicles, but it is not sorted into small budded vesicles. We found both cTAGE5 and SEC12 were exported with TANGO1 in large COPII carriers. In contrast to its exclusion from small transport vesicles, SEC12 was particularly enriched around ER membranes and large COPII carriers that contained PC1. We constructed a split GFP system to recapitulate the targeting of SEC12 to PC1 via the luminal domain of TANGO1. The minimal targeting system enriched SEC12 around PC1 and generated large PC1 carriers. We conclude that TANGO1, cTAGE5, and SEC12 are copacked with PC1 into COPII carriers to increase the size of COPII, thus ensuring the capture of large cargo.

An integral membrane protein antigen associated with the membrane attachment sites of actin microfilaments is identified as an integrin beta-chain

1988 ◽  
Vol 8 (2) ◽  
pp. 564-570
Author(s):  
P A Maher ◽  
S J Singer
Keyword(s):  
Molecular Weight ◽  
Membrane Protein ◽  
Protein Complex ◽  
Apparent Molecular Weight ◽  
Integral Membrane Protein ◽  
Beta Chain ◽  
Attachment Sites ◽  
Wide Range ◽  
Membrane Attachment

A monoclonal antibody (MAb 30B6) was recently described by Rogalski and Singer (J. Cell Biol. 101:785-801, 1985) which identified an integral membrane glycoprotein of chicken cells that was associated with a wide variety of sites of actin microfilament attachments to membranes. In this report, we present a further characterization of this integral protein. An immunochemical comparison was made of MAb 30B6 binding properties with those of two other MAbs, JG9 and JG22, which identify a component of a membrane protein complex that interacts with extracellular matrix proteins including fibronectin. We showed that the 110-kilodalton protein recognized by MAb 30B6 in extracts of chicken gizzard smooth muscle is identical, or closely related, to the protein that reacts with MAbs JG9 and JG22. These 110-kilodalton proteins are also structurally closely similar, if not identical, to one another as demonstrated by 125I-tryptic peptide maps. However, competition experiments showed that MAb 30B6 recognizes a different epitope from those recognized by MAbs JG9 and JG22. In addition, the 30B6 antigen is part of a complex that can be isolated on fibronectin columns. These results together establish that the 30B6 antigen is the same as, or closely similar to, the beta-chain of the protein complex named integrin, which is the complex on chicken fibroblast membranes that binds fibronectin. Although the 30B6 antigen is present in a wide range of tissues, its apparent molecular weight on gels varies in different tissues. These differences in apparent molecular weight are due, in large part, to differences in glycosylation.

PLATELETS EXPRESS A MEMBRANE PROTEIN COMPLEX IMMUNOLOGICALLY RELATED TO THE FIBROBLAST FIBRONECTIN RECEPTOR

1987 ◽  
Author(s):  
F G Giancotti ◽  
L R Languino ◽  
A Zanetti ◽  
G Grignani ◽  
G Tarone ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Western Blot ◽  
Protein Complex ◽  
Polyclonal Antibodies ◽  
Flow Cytometric Analysis ◽  
Integral Membrane Protein ◽  
Human Platelets ◽  
Mouse Fibroblast ◽  
Platelet Surface ◽  
Fibronectin Receptor

The heterodimer complex GpIIb-IIIa on human platelets can specifically bind fibronectin (FN) only when platelets are activated by thrombin. However unstimulated platelets can adhere and spread on a FN substratum. This suggests the existence of a second binding site for FN on the platelet surface that does not require activation for its expression. We have previously identified and characterized a membrane glycoprotein complex (Gp 150/135) that functions as fibronectin receptor (FN-R) in mouse fibroblast adhesion. To investigate whether this molecule was also present in platelets we have produced an affinity purified polyclonal antibodies monospecific for the lower subunit of the fibroblast FN-R. These antibodies specifically stained human and rat platelet surface as determined by fluorescence flow cytometric analysis and reacted with a component of 138 Kd m w in Western blot of platelet membranes. Experiments of differential extraction revealed that the 138 Kd component is an integral membrane protein. Moreover the antibodies precipitated the 138 Kd component together with a 160 Kd protein suggesting that the two molecules are associated in a supramolecular complex. A comparative analysis indicated that this protein complex is clearly distinct from the GpIIb-IIIa. In addition platelets from a thrombastenic patient reacted normally with 138 Kd but not with GpIIb-IIIa antibodies by Western blot analysis. These data indicate that normal human platelets express both GpIIb-IIIa and FN-R on their membrane and that these receptors are composed of structurally and antigenically distinct proteins.

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