Sec24 Proteins and Sorting at the Endoplasmic Reticulum

Pagano, Alessandra; Letourneur, François; Garcia-Estefania, David; Carpentier, Jean‐Louis; Orci, Lelio; Paccaud, Jean‐Pierre

doi:10.1074/jbc.274.12.7833

Cited by 124 publications

(97 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…After addition of a GTP-restricted mutant of Sar1 fused to glutathione Stransferase (GST-Sar1-GTP), these prebudding complexes are isolated from detergent solubilized membranes using glutathione agarose beads. Mammalian cells contain two genes coding for Sec23 (A and B) and four genes for Sec24 (A-D) (17,18). We used a baculovirus expression system to produce a complex of Sec23A and Sec24C (see Fig.…”

Section: Resultsmentioning

confidence: 99%

Sterols block binding of COPII proteins to SCAP, thereby controlling SCAP sorting in ER

Espenshade

Yabe

2002

Proc. Natl. Acad. Sci. U.S.A.

135

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 99%

Sterols block binding of COPII proteins to SCAP, thereby controlling SCAP sorting in ER

Espenshade

Yabe

2002

Proc. Natl. Acad. Sci. U.S.A.

135

View full text Add to dashboard Cite

“…A null mutant of lst1 is viable, although sensitive to low pH resulting from a reduced flux of Pma1p out of the ER (15). Efficient incorporation of Pma1p into COPII vesicles requires a combination of both Sec24p and Lst1p complexes, unlike other cargo proteins studied to date (16). In addition to the enhancement of Pma1p packaging, Lst1p-positive vesicles are ϳ15% larger than vesicles generated with standard COPII subunits (17).…”

mentioning

confidence: 90%

“…Homologs of Sec24p have been identified in yeast and mammals (15,16) and may act to diversify the range of cargo proteins recruited into a nascent vesicle. In yeast, the Sec24p homolog Lst1p was discovered in a screen for synthetic interactions with the sec13-1 allele (lethal with sec-thirteen) (15).…”

mentioning

confidence: 99%

Ceramide Biosynthesis Is Required for the Formation of the Oligomeric H+-ATPase Pma1p in the Yeast Endoplasmic Reticulum

Lee¹,

Hamamoto

Schekman

2002

Journal of Biological Chemistry

125

154

View full text Add to dashboard Cite

The yeast plasma membrane H؉ -ATPase Pma1p is one of the most abundant proteins to traverse the secretory pathway. Newly synthesized Pma1p exits the endoplasmic reticulum (ER) via COPII-coated vesicles bound for the Golgi. Unlike most secreted proteins, efficient incorporation of Pma1p into COPII vesicles requires the Sec24p homolog Lst1p, suggesting a unique role for Lst1p in ER export. Vesicles formed with mixed Sec24p-Lst1p coats are larger than those with Sec24p alone. Here, we examined the relationship between Pma1p biosynthesis and the requirement for this novel coat subunit. We show that Pma1p forms a large oligomeric complex of >1 MDa in the ER, which is packaged into COPII vesicles. Furthermore, oligomerization of Pma1p is linked to membrane lipid composition; Pma1p is rendered monomeric in cells depleted of ceramide, suggesting that association with lipid rafts may influence oligomerization. Surprisingly, monomeric Pma1p present in ceramide-deficient membranes can be exported from the ER in COPII vesicles in a reaction that is stimulated by Lst1p. We suggest that Lst1p directly conveys Pma1p into a COPII vesicle and that the larger size of mixed Sec24pLst1p COPII vesicles is not essential to the packaging of large oligomeric complexes.An essential protein of the yeast plasma membrane is the H ϩ -ATPase Pma1p. At steady state, it composes Ͼ25% of the total protein at the plasma membrane, where it generates a proton gradient that maintains the intracellular pH and drives the import of nutrients (1). Pma1p spans the lipid bilayer with 10 transmembrane segments and belongs to the family of P 2 -type ATPases, which includes the Na ϩ ,K ϩ -ATPases and Ca 2ϩ -ATPases of the mammalian plasma membrane (2, 3).As with other integral membrane proteins destined for the plasma membrane, Pma1p is translocated into the endoplasmic reticulum (ER) 1 and travels through a series of transport vesicles to its final destination (4, 5). En route, Pma1p and the glycosylphosphatidylinositol-anchored protein Gas1p become associated with lipid rafts (6, 7). Interestingly, raft association of Gas1p initiates in the ER (6), unlike in mammalian cells, where glycosylphosphatidylinositol-anchored proteins enter rafts in post-ER compartments (8, 9). Exit out of the ER is mediated by COPII (coat protein complex II) vesicles, a universal mechanism in eukaryotes employing a set of cytoplasmic coat proteins (10). Budding is regulated by the small G-protein Sar1p, which recruits two complexes, Sec23p-Sec24p and Sec13p-Sec31p (10 -12). Assembly of these three components on the surface of liposomes is sufficient to deform the lipid bilayer to generate small coated vesicles (11). On the ER membrane, Sar1p and Sec23p-Sec24p promote the capture of a number of cargo proteins, suggesting that Sec23p-Sec24p may function to selectively engage cargo proteins during coat assembly (13,14).Homologs of Sec24p have been identified in yeast and mammals (15, 16) and may act to diversify the range of cargo proteins recruited into a nascent vesicle. In yeast...

show abstract

“…Various functions are attributed to coated vesicles, which are defined by their constituent coat proteins. Isoforms with different combinations of coat protein complex (COP)II protein paralogs have been found in the COPII coats on vesicles budding from the endoplasmic reticulum (ER) of mammals and yeast (1)(2)(3). Because only one direction of travel from the ER to the Golgi apparatus is known for COPII vesicles, these isoforms might reflect differing cargo specificities (4).…”

mentioning

confidence: 99%

Differential localization of coatomer complex isoforms within the Golgi apparatus

Moelleken

Malsam

Betts

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Coatomer, the coat protein of coat protein complex (COP)I-vesicles, is a soluble protein complex made up of seven subunits, ␣-, ␤-, ␤ -, ␥-, ␦-, -, and -COP. Higher eukaryotes have two paralogous versions of the ␥-and -subunits, termed ␥1-and ␥2-COP and 1-and 2-COP. Different combinations of these subunits are known to exist within coatomer complexes, and ␥1/ 1-, ␥1/ 2-, and ␥2/ 1-COP represent the major coatomer populations in mammals. The role of COPI vesicles in the early secretory pathway is the subject of considerable debate. To help to resolve this discussion, we used quantitative immunoelectron microscopy and found that significant localization differences for COPI-isoforms do exist, with a preference for ␥1 1-and ␥1 2-coatomer in the early Golgi apparatus and ␥2 1-coatomer in the late Golgi apparatus. These differences suggest distinct functions for coatomer isoforms in a manner similar to clathrin/adaptor vesicles, where different adaptor proteins serve particular transport routes.coat protein complex I ntracellular vesicular transport is mediated by small proteincoated carriers. Various functions are attributed to coated vesicles, which are defined by their constituent coat proteins. Isoforms with different combinations of coat protein complex (COP)II protein paralogs have been found in the COPII coats on vesicles budding from the endoplasmic reticulum (ER) of mammals and yeast (1-3). Because only one direction of travel from the ER to the Golgi apparatus is known for COPII vesicles, these isoforms might reflect differing cargo specificities (4). In the late Golgi/endocytic pathways, a variety of coat proteins are known, including four different tetrameric adaptor complexes, some of which use the clathrin system as an outer shell of their coat (5). Within these pathways, particular transport routes are served by specific coat complexes (for review, see refs. 6 and 7). Thus, for particular pathways, the selection of cargo as well as the direction might be determined by individual coats.Just which pathways are mediated by vesicles bearing the COPI coat is the subject of considerable debate. The COPI coat consists of coatomer, which is a stable cytoplasmic complex of seven subunits, ␣-, ␤-, ␤Ј-, ␥-, ␦-, -, and -COP, and the small GTP-binding protein ADP-ribosylation factor, Arf1. COPI vesicles were found to originate from the Golgi apparatus and are implicated in transport within the Golgi itself in anterograde and retrograde direction, and from the Golgi and the ER-Golgi intermediate compartment (ERGIC) to the ER (8-10). The observation that COPI vesicles participate in several transport directions is difficult to rationalize with just a single isoform of the complex (reviewed in ref. 11). Questions about the function of COPI vesicles are intimately linked to our view of the general mechanisms of transport through the Golgi. Specifically, is transport in both directions, anterograde and retrograde, performed by these carriers, or are COPI vesicles exclusively retrograde carriers within the Golgi and from...

show abstract

Sec24 Proteins and Sorting at the Endoplasmic Reticulum

Cited by 124 publications

References 45 publications

Sterols block binding of COPII proteins to SCAP, thereby controlling SCAP sorting in ER

Sterols block binding of COPII proteins to SCAP, thereby controlling SCAP sorting in ER

Ceramide Biosynthesis Is Required for the Formation of the Oligomeric H+-ATPase Pma1p in the Yeast Endoplasmic Reticulum

Differential localization of coatomer complex isoforms within the Golgi apparatus

Contact Info

Product

Resources

About