scholarly journals Yos1p Is a Novel Subunit of the Yip1p–Yif1p Complex and Is Required for Transport between the Endoplasmic Reticulum and the Golgi Complex

2005 ◽  
Vol 16 (4) ◽  
pp. 1673-1683 ◽  
Author(s):  
Matthew Heidtman ◽  
Catherine Z. Chen ◽  
Ruth N. Collins ◽  
Charles Barlowe
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Secretory Pathway ◽  
Integral Membrane Protein ◽  
Rab Gtpases ◽  
Reading Frame ◽  
Multicopy Suppressor ◽  
Transport Vesicles ◽  
Identification And Characterization

Yeast Yip1p is a member of a conserved family of transmembrane proteins that interact with Rab GTPases. Previous studies also have indicated a role for Yip1p in the biogenesis of endoplasmic reticulum (ER)-derived COPII transport vesicles. In this report, we describe the identification and characterization of the uncharacterized open reading frame YER074W-A as a novel multicopy suppressor of the thermosensitive yip1-4 strain. We have termed this gene Yip One Suppressor 1 (YOS1). Yos1p is essential for growth and for function of the secretory pathway; depletion or inactivation of Yos1p blocks transport between the ER and the Golgi complex. YOS1 encodes an integral membrane protein of 87 amino acids that is conserved in eukaryotes. Yos1p localizes to ER and Golgi membranes and is efficiently packaged into ER-derived COPII transport vesicles. Yos1p associates with Yip1p and Yif1p, indicating Yos1p is a novel subunit of the Yip1p–Yif1p complex.

scholarly journals KDEL and KKXX Retrieval Signals Appended to the Same Reporter Protein Determine Different Trafficking between Endoplasmic Reticulum, Intermediate Compartment, and Golgi Complex

2003 ◽  
Vol 14 (3) ◽  
pp. 889-902 ◽  
Author(s):  
Mariano Stornaiuolo ◽  
Lavinia V. Lotti ◽  
Nica Borgese ◽  
Maria-Rosaria Torrisi ◽  
Giovanna Mottola ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Steady State ◽  
Golgi Complex ◽  
Secretory Pathway ◽  
Molecular Mechanisms ◽  
Reporter Protein ◽  
Transport Vesicles ◽  
Efficient Retrieval ◽  
Intermediate Compartment ◽  
Almost All

Many endoplasmic reticulum (ER) proteins maintain their residence by dynamic retrieval from downstream compartments of the secretory pathway. In previous work we compared the retrieval process mediated by the two signals, KKMP and KDEL, by appending them to the same neutral reporter protein, CD8, and found that the two signals determine a different steady-state localization of the reporter. CD8-K (the KDEL-bearing form) was restricted mainly to the ER, whereas CD8-E19 (the KKMP-bearing form) was distributed also to the intermediate compartment and Golgi complex. To investigate whether this different steady-state distribution reflects a difference in exit rates from the ER and/or in retrieval, we have now followed the first steps of export of the two constructs from the ER and their trafficking between ER and Golgi complex. Contrary to expectation, we find that CD8-K is efficiently recruited into transport vesicles, whereas CD8-E19 is not. Thus, the more restricted ER localization of CD8-K must be explained by a more efficient retrieval to the ER. Moreover, because most of ER resident CD8-K is not O-glycosylated but almost all CD8-E19 is, the results suggest that CD8-K is retrieved from the intermediate compartment, before reaching the Golgi, whereO-glycosylation begins. These results illustrate how different retrieval signals determine different trafficking patterns and pose novel questions on the underlying molecular mechanisms.

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 ERS-24, a Mammalian v-SNARE Implicated in Vesicle Traffic between the ER and the Golgi

1997 ◽  
Vol 137 (5) ◽  
pp. 1017-1028 ◽  
Author(s):  
Inbok Paek ◽  
Lelio Orci ◽  
Mariella Ravazzola ◽  
Hediye Erdjument-Bromage ◽  
Mylene Amherdt ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Sequence Homology ◽  
Vesicular Transport ◽  
Dependent Manner ◽  
Vesicle Traffic ◽  
Transport Vesicles ◽  
Identification And Characterization

We report the identification and characterization of ERS-24 (Endoplasmic Reticulum SNARE of 24 kD), a new mammalian v-SNARE implicated in vesicular transport between the ER and the Golgi. ERS24 is incorporated into 20S docking and fusion particles and disassembles from this complex in an ATP-dependent manner. ERS-24 has significant sequence homology to Sec22p, a v-SNARE in Saccharomyces cerevisiae required for transport between the ER and the Golgi. ERS-24 is localized to the ER and to the Golgi, and it is enriched in transport vesicles associated with these organelles.

scholarly journals Differential Induction of Two p24δ Putative Cargo Receptors upon Activation of a Prohormoneproducing Cell

2000 ◽  
Vol 11 (1) ◽  
pp. 131-140 ◽  
Author(s):  
Roland P. Kuiper ◽  
Hans R. Waterham ◽  
Jutta Rötter ◽  
Gerrit Bouw ◽  
Gerard J. M. Martens
Keyword(s):  
Secretory Pathway ◽  
Protein Transport ◽  
Fold Increase ◽  
Type I ◽  
Black Background ◽  
Background Adaptation ◽  
Cargo Transport ◽  
Transport Vesicles ◽  
Identification And Characterization

The p24 family consists of type I transmembrane proteins that are present abundantly in transport vesicles, may play a role in endoplasmic reticulum-to-Golgi cargo transport, and have been classified into subfamilies named p24α, -β, -γ, and -δ. We previously identified a member of the p24δ subfamily that is coordinately expressed with the prohormone proopiomelanocortin (POMC) in the melanotrope cells of the intermediate pituitary during black background adaptation of the amphibian Xenopus laevis(∼30-fold increase in POMC mRNA). In this study, we report on the characterization of this p24δ member (Xp24δ2) and on the identification and characterization of a second member (Xp24δ1) that is also expressed in the melanotrope cells and that has 66% amino acid sequence identity to Xp24δ2. The two p24δ members are ubiquitously expressed, but Xp24δ2 is neuroendocrine enriched. During black background adaptation, the amount of the Xp24δ2 protein in the intermediate pituitary was increased ∼25 times, whereas Xp24δ1 protein expression was increased only 2.5 times. Furthermore, the level of Xp24δ2 mRNA was ∼5-fold higher in the melanotrope cells of black-adapted animals than in those of white-adapted animals, whereas Xp24δ1 mRNA expression was not induced. Therefore, the expression of Xp24δ2specifically correlates with the expression of POMC. Together, our findings suggest that p24δ proteins have a role in selective protein transport in the secretory pathway.

The yeast SLY gene products, suppressors of defects in the essential GTP-binding Ypt1 protein, may act in endoplasmic reticulum-to-Golgi transport

1991 ◽  
Vol 11 (6) ◽  
pp. 2980-2993
Author(s):  
R Ossig ◽  
C Dascher ◽  
H H Trepte ◽  
H D Schmitt ◽  
D Gallwitz
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Pathway ◽  
Protein Transport ◽  
Single Copy ◽  
Integral Membrane Protein ◽  
Carboxypeptidase Y ◽  
Null Mutant ◽  
Yeast Saccharomyces Cerevisiae ◽  
Golgi Transport ◽  
Gtp Binding

It has been shown previously that defects in the essential GTP-binding protein, Ypt1p, lead to a block in protein transport from the endoplasmic reticulum (ER) to the Golgi apparatus in the yeast Saccharomyces cerevisiae. Here we report that four newly discovered suppressors of YPT1 deletion (SLY1-20, SLY2, SLY12, and SLY41) to a varying degree restore ER-to-Golgi transport defects in cells lacking Ypt1p. These suppressors also partially complement the sec21-1 and sec22-3 mutants which lead to a defect early in the secretory pathway. Sly1p-depleted cells, as well as a conditional lethal sly2 null mutant at nonpermissive temperatures, accumulate ER membranes and core-glycosylated invertase and carboxypeptidase Y. The sly2 null mutant under restrictive conditions (37 degrees C) can be rescued by the multicopy suppressor SLY12 and the single-copy suppressor SLY1-20, indicating that these three SLY genes functionally interact. Sly2p is shown to be an integral membrane protein.

scholarly journals New Mutants of Saccharomyces cerevisiae Affected in the Transport of Proteins From the Endoplasmic Reticulum to the Golgi Complex

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 393-406 ◽  
Author(s):  
Linda J Wuestehube ◽  
Rainer Duden ◽  
Arlene Eun ◽  
Susan Hamamoto ◽  
Paul Korn ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Secretory Pathway ◽  
Secretory Protein ◽  
Temperature Sensitive ◽  
Nonpermissive Temperature ◽  
Membrane Structures ◽  
Α Subunit ◽  
Complementation Groups ◽  
Vacuolar Protein

Abstract We have isolated new temperature-sensitive mutations in five complementation groups, sec31-sec35, that are defective in the transport of proteins from the endoplasmic reticulum (ER) to the Golgi complex. The sec31-sec35 mutants and additional alleles of previously identified sec and vacuolar protein sorting (vps) genes were isolated in a screen based on the detection of α-factor precursor in yeast colonies replicated to and lysed on nitrocellulose filters. Secretory protein precursors accumulated in sec31-sec35 mutants at the nonpermissive temperature were core-glycosylated but lacked outer chain carbohydrate, indicating that transport was blocked after translocation into the ER but before arrival in the Golgi complex. Electron microscopy revealed that the newly identified sec mutants accumulated vesicles and membrane structures reminiscent of secretory pathway organelles. Complementation analysis revealed that sec32-1 is an allele of BOS1, a gene implicated in vesicle targeting to the Golgi complex, and sec33-1 is an allele of RET1, a gene that encodes the α subunit of coatomer.

scholarly journals Pathogenic Effects of Impaired Retrieval between the Endoplasmic Reticulum and Golgi Complex

2019 ◽  
Vol 20 (22) ◽  
pp. 5614 ◽  
Author(s):  
Hiroshi Kokubun ◽  
Hisayo Jin ◽  
Tomohiko Aoe
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Secretory Pathway ◽  
Protein Transport ◽  
Receptor Activation ◽  
Toxic Substances ◽  
Bidirectional Transport ◽  
The Unfolded Protein Response ◽  
Kdel Receptor ◽  
Kdel Sequence

Cellular activities, such as growth and secretion, are dependent on correct protein folding and intracellular protein transport. Injury, like ischemia, malnutrition, and invasion of toxic substances, affect the folding environment in the endoplasmic reticulum (ER). The ER senses this information, following which cells adapt their response to varied situations through the unfolded protein response. Activation of the KDEL receptor, resulting from the secretion from the ER of chaperones containing the KDEL sequence, plays an important role in this adaptation. The KDEL receptor was initially shown to be necessary for the retention of KDEL sequence-containing proteins in the ER. However, it has become clear that the activated KDEL receptor also regulates bidirectional transport between the ER and the Golgi complex, as well as from the Golgi to the secretory pathway. In addition, it has been suggested that the signal for KDEL receptor activation may also affect several other cellular activities. In this review, we discuss KDEL receptor-mediated bidirectional transport and signaling and describe disease models and human diseases related to KDEL receptor dysfunction.

scholarly journals Identification and Characterization of Aspergillus nidulans Mutants Impaired in Asexual Development under Phosphate Stress

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1520 ◽  
Author(s):  
Ainara Otamendi ◽  
Eduardo A. Espeso ◽  
Oier Etxebeste
Keyword(s):  
Transcription Factor ◽  
Aspergillus Nidulans ◽  
Genomic Library ◽  
Phenotypic Trait ◽  
Mutant Form ◽  
Multicopy Suppressor ◽  
Putative Transcription Factor ◽  
Recessive Mutant ◽  
Identification And Characterization

The transcription factor BrlA plays a central role in the production of asexual spores (conidia) in the fungus Aspergillus nidulans. BrlA levels are controlled by signal transducers known collectively as UDAs. Furthermore, it governs the expression of CDP regulators, which control most of the morphological transitions leading to the production of conidia. In response to the emergence of fungal cells in the air, the main stimulus triggering conidiation, UDA mutants such as the flbB deletant fail to induce brlA expression. Nevertheless, ΔflbB colonies conidiate profusely when they are cultured on a medium containing high H2PO4− concentrations, suggesting that the need for FlbB activity is bypassed. We used this phenotypic trait and an UV-mutagenesis procedure to isolate ΔflbB mutants unable to conidiate under these stress conditions. Transformation of mutant FLIP166 with a wild-type genomic library led to the identification of the putative transcription factor SocA as a multicopy suppressor of the FLIP (Fluffy, aconidial, In Phosphate) phenotype. Deregulation of socA altered both growth and developmental patterns. Sequencing of the FLIP166 genome enabled the identification and characterization of PmtCP282L as the recessive mutant form responsible for the FLIP phenotype. Overall, results validate this strategy for identifying genes/mutations related to the control of conidiation.

scholarly journals Requirement for Neo1p in Retrograde Transport from the Golgi Complex to the Endoplasmic Reticulum

2003 ◽  
Vol 14 (12) ◽  
pp. 4971-4983 ◽  
Author(s):  
Zhaolin Hua ◽  
Todd R. Graham
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Secretory Pathway ◽  
Protein Transport ◽  
Retrograde Transport ◽  
Transport Pathway ◽  
Transport Defect ◽  
Copii Vesicles ◽  
P Type ◽  
Adp Ribosylation Factor

Neo1p from Saccharomyces cerevisiae is an essential P-type ATPase and potential aminophospholipid translocase (flippase) in the Drs2p family. We have previously implicated Drs2p in protein transport steps in the late secretory pathway requiring ADP-ribosylation factor (ARF) and clathrin. Here, we present evidence that epitope-tagged Neo1p localizes to the endoplasmic reticulum (ER) and Golgi complex and is required for a retrograde transport pathway between these organelles. Using conditional alleles of NEO1, we find that loss of Neo1p function causes cargo-specific defects in anterograde protein transport early in the secretory pathway and perturbs glycosylation in the Golgi complex. Rer1-GFP, a protein that cycles between the ER and Golgi complex in COPI and COPII vesicles, is mislocalized to the vacuole in neo1-ts at the nonpermissive temperature. These phenotypes suggest that the anterograde protein transport defect is a secondary consequence of a defect in a COPI-dependent retrograde pathway. We propose that loss of lipid asymmetry in the cis Golgi perturbs retrograde protein transport to the ER.

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