The absence of Emp24p, a component of ER-derived COPII-coated vesicles, causes a defect in transport of selected proteins to the Golgi.

Schimmöller, Frauke; Singer-Krüger, Birgit; Schröder, Stephan; Krüger, Ute; Barlowe, Charles; Riezman, Howard

doi:10.1002/j.1460-2075.1995.tb07119.x

Cited by 324 publications

(344 citation statements)

References 71 publications

(54 reference statements)

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Section: Erv26p Is An Integral Membrane Protein That Cycles Between Tsupporting

confidence: 80%

“…Under steady state conditions, ϳ60% of the Erv26p cofractionated with the Golgi marker protein Och1p and ϳ40% with the ER marker Sec61p. This subcellular distribution pattern was similar to other COPII vesicles proteins including Emp24p, Erv46p and ER/Golgi SNARE proteins (Schimmoller et al, 1995;Otte et al, 2001;Cao and Barlowe, 2000).To test whether Erv26p dynamically cycles between the ER and Golgi compartments in vivo, we monitored the fate of this protein in a sec12 mutant strain. The sec12 mutation blocks COPII budding when shifted to a restrictive temperature (Kaiser and Schekman, 1990); therefore, if Erv26p actively cycles between the ER and Golgi, we would expect it to accumulate in the ER under a sec12 block.…”

supporting

confidence: 63%

“…Our approach has been to investigate the function of abundant ER vesicle proteins (Ervs) that are enriched in purified COPII vesicle preparations (Otte et al, 2001). Several of the Erv proteins are involved in cargo sorting and when mutated they produce selective protein sorting defects (Schimmoller et al, 1995;Belden and Barlowe, 1996;Powers and Barlowe, 1998;Belden and Barlowe, 2001). In this report, we identify and characterize a new cargo-specific ER export factor, Erv26p.…”

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confidence: 94%

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

Bue

Bentivoglio

Barlowe

2006

MBoC

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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 erv26⌬ 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. INTRODUCTIONThe eukaryotic secretory pathway transports a remarkable variety of cargo proteins to their proper cellular location. Several lines of evidence indicate that targeting information encoded within a secretory protein is recognized by the intracellular transport machinery to direct localization. Cytosolic coat protein complexes play an important role in deciphering targeting information and act in the selection of secretory proteins into appropriate transport intermediates (Bonifacino and Glick, 2004). However, the sorting signals and mechanisms by which coat complexes accommodate such diversity in secretory cargo remain poorly understood.Protein transport from the endoplasmic reticulum (ER) relies on coat protein complex II (COPII), which selects fully folded secretory cargo into ER-derived transport intermediates. COPII coats consist of the small GTPase Sar1p, the Sec23/24 complex, and the Sec13/31 complex (Barlowe et al., 1994). Biochemical and structural studies have demonstrated that the Sec24p subunit of this coat complex contains multiple cargo recognition sites and binds specific sorting signals displayed on the cytosolic regions of secretory proteins (Miller et al., 2003;Mossessova et al., 2003). Diacidic sequences and other polypeptide sorting signals have been identified in cargo proteins that interact with amino acid residues within defined Sec24p cargo recognition sites. Current models envisage that the cargo recognition and binding by Sec24p is stabilized through assembly of prebudding complexes consisting of Sec23/24 and Sar1p-GTP bound to secretory cargo on the ER membrane surface. These prebudding complexes are then incorporated into an outer layer Sec13/31 scaffold structure that deforms the membrane and produces COPII-coated vesicles (Lee et al., 2004;Stagg et al., 2006).In addition to the COPII coat proteins, cargo-specific accessory factors are required to accommodate the variety of secretory cargo exported from the ER in CO...

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Section: Erv26p Is An Integral Membrane Protein That Cycles Between Tsupporting

confidence: 80%

supporting

confidence: 63%

mentioning

confidence: 94%

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

Bue

Bentivoglio

Barlowe

2006

MBoC

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“…Therefore, secretion of Kar2p into the growth medium was analyzed. In contrast to an emp24⌬ mutant strain that lacks one of eight members of the yeast p24 family of cargo receptors (Schimmö ller et al, 1995;ElrodErickson and Kaiser, 1996), the desaturase mutant strain did Wild-type (W303, A) and ole1 ts mutant cells (YRS1327, B and C) were grown at 30°C to the early logarithmic phase and shifted to 37°C for 15 min (A and B) or left at 30°C (C). Cells were fixed and prepared for ultrastructural analysis by electron microscopy.…”

Section: Relocalization Of the Mutant Desaturase Does Not Affect The mentioning

confidence: 99%

Lipid-dependent Subcellular Relocalization of the Acyl Chain Desaturase in Yeast

Tatzer¹,

Zellnig

Kohlwein

et al. 2002

MBoC

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The degree of acyl chain desaturation of membrane lipids is a critical determinant of membrane fluidity. Temperature-sensitive mutants of the single essential acyl chain desaturase, Ole1p, of yeast have previously been isolated in screens for mitochondrial inheritance mutants (Stewart, L.C., and Yaffe, M.P. ). J. Cell Biol. 115, 1249 -1257. We now report that the mutant desaturase relocalizes from its uniform ER distribution to a more punctuate localization at the cell periphery upon inactivation of the enzyme. This relocalization takes place within minutes at nonpermissive conditions, a time scale at which mitochondrial morphology and inheritance is not yet affected. Relocalization of the desaturase is fully reversible and does not affect the steady state localization of other ER resident proteins or the kinetic and fidelity of the secretory pathway, indicating a high degree of selectivity for the desaturase. Relocalization of the desaturase is energy independent but is lipid dependent because it is rescued by supplementation with unsaturated fatty acids. Relocalization of the desaturase is also observed in cells treated with inhibitors of the enzyme, indicating that it is independent of temperature-induced alterations of the enzyme. In the absence of desaturase function, lipid synthesis continues, resulting in the generation of lipids with saturated acyl chains. A model is discussed in which the accumulation of saturated lipids in a microdomain around the desaturase could induce the observed segregation and relocalization of the enzyme.

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“…Yet another major cargo receptor is Emp24p in yeast. Emp24p is the founding member of the p24 protein family (Kaiser, 2000), and it is required for efficient ER-to-Golgi transport of glycosylphosphatidylinositol-anchored proteins (Schimmoller et al, 1995;Muniz et al, 2000). It is conceivable that mammalian p24 proteins also operate as cargo receptors although no cargo protein has been identified.…”

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confidence: 99%

The Cargo Receptors Surf4, Endoplasmic Reticulum-Golgi Intermediate Compartment (ERGIC)-53, and p25 Are Required to Maintain the Architecture of ERGIC and Golgi

Mitrović

Ben-Tekaya

Koegler

et al. 2008

MBoC

115

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Rapidly cycling proteins of the early secretory pathway can operate as cargo receptors. Known cargo receptors are abundant proteins, but it remains mysterious why their inactivation leads to rather limited secretion phenotypes. Studies of Surf4, the human orthologue of the yeast cargo receptor Erv29p, now reveal a novel function of cargo receptors. Surf4 was found to interact with endoplasmic reticulum-Golgi intermediate compartment (ERGIC)-53 and p24 proteins. Silencing Surf4 together with ERGIC-53 or silencing the p24 family member p25 induced an identical phenotype characterized by a reduced number of ERGIC clusters and fragmentation of the Golgi apparatus without effect on anterograde transport. Live imaging showed decreased stability of ERGIC clusters after knockdown of p25. Silencing of Surf4/ERGIC-53 or p25 resulted in partial redistribution of coat protein (COP) I but not Golgi matrix proteins to the cytosol and partial resistance of the cis-Golgi to brefeldin A. These findings imply that cargo receptors are essential for maintaining the architecture of ERGIC and Golgi by controlling COP I recruitment. INTRODUCTIONThe secretory pathway of higher eukaryotic cells is composed of the three membrane organelles endoplasmic reticulum (ER), ER-Golgi intermediate compartment (ERGIC), and Golgi (Bonifacino and Glick, 2004;Appenzeller-Herzog and Hauri, 2006). Maintenance of these organelles requires a balance of anterograde (secretory) and retrograde vesicular traffic. Anterograde traffic from ER to ERGIC is mediated by coat protein (COP) II vesicles that form at ER exit sites (Aridor et al., 1995;Zeuschner et al., 2006) and fuse with the ERGIC that consists of a few hundred tubulovesicular membrane clusters in vicinity of ER exit sites (AppenzellerHerzog and Hauri, 2006). Transport from ERGIC to Golgi is mediated by pleomorphic vesicles (Ben-Tekaya et al., 2005) that carry COP I (Presley et al., 1997;Scales et al., 1997), although the mechanism of their formation remains unknown. Retrograde traffic mediated by COP I vesicles can occur from ERGIC or Golgi and recycles membrane proteins that possess either dilysine signals, including ERGIC-53 and KDEL-receptor, or diphenylalanine signals, such as members of the 24 protein family. This rapid COP I-dependent recycling is distinct from the slow Golgi-to-ER recycling of Golgi resident proteins that is COP I independent and can be either constitutive or induced (Storrie, 2005).Major constituents of anterograde and retrograde transport vesicles are transmembrane cargo receptors that mediate protein sorting by linking soluble cargo on the luminal side and coat assembly on the cytoplasmic side. To date, only few cargo receptors have been studied in detail. The polytopic transmembrane protein Erv29p is known to cycle between ER and Golgi in yeast and to operate as a cargo receptor (Belden and Barlowe, 2001). Erv29p is required for efficient packaging of the glycosylated ␣-factor pheromone precursor into COP II vesicles departing from the ER. Maturation of carboxypeptidase Y...

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The absence of Emp24p, a component of ER-derived COPII-coated vesicles, causes a defect in transport of selected proteins to the Golgi.

Cited by 324 publications

References 71 publications

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

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

Lipid-dependent Subcellular Relocalization of the Acyl Chain Desaturase in Yeast

The Cargo Receptors Surf4, Endoplasmic Reticulum-Golgi Intermediate Compartment (ERGIC)-53, and p25 Are Required to Maintain the Architecture of ERGIC and Golgi

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