scholarly journals Control of Golgi Morphology and Function by Sed5 t-SNARE Phosphorylation

2005 ◽  
Vol 16 (10) ◽  
pp. 4918-4930 ◽  
Author(s):  
Adina Weinberger ◽  
Faustin Kamena ◽  
Rachel Kama ◽  
Anne Spang ◽  
Jeffrey E. Gerst
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Trafficking ◽  
Retrograde Transport ◽  
Cell Types ◽  
Intracellular Protein ◽  
Inhibition Of Growth ◽  
Golgi Transport ◽  
Transport Vesicles ◽  
And Function ◽  
Kinase A

Previously, we demonstrated that the phosphorylation of t-SNAREs by protein kinase A (PKA) affects their ability to participate in SNARE complexes and to confer endocytosis and exocytosis in yeast. Here, we show that the presumed phosphorylation of a conserved membrane-proximal PKA consensus site (serine-317) in the Sed5 t-SNARE regulates endoplasmic reticulum (ER)-Golgi transport, as well as Golgi morphology. Sed5 is a phosphoprotein, and both alanine and aspartate substitutions in serine-317 directly affect intracellular protein trafficking. The aspartate substitution results in elaboration of the ER, defects in Golgi-ER retrograde transport, an accumulation of small transport vesicles, and the inhibition of growth of most cell types. In contrast, the alanine substitution has no deleterious effects upon transport and growth, but results in ordering of the Golgi into a structure reminiscent of mammalian apparatus. This structure seems to require the recycling of Sed5, because it was found not to occur in sec21-2 cells that are defective in retrograde transport. Thus, a cycle of Sed5 phosphorylation and dephosphorylation is required for normal t-SNARE function and may choreograph Golgi ordering and dispersal.

scholarly journals Selective Protein Exit from Yeast Endoplasmic Reticulum in Absence of Functional COPII Coat Component Sec13p

2002 ◽  
Vol 13 (12) ◽  
pp. 4130-4140 ◽  
Author(s):  
Netta Fatal ◽  
Taina Suntio ◽  
Marja Makarow
Keyword(s):  
Endoplasmic Reticulum ◽  
Functional Form ◽  
Protein S ◽  
Normal Function ◽  
Essential Component ◽  
Exchange Factor ◽  
Terminal Domain ◽  
Golgi Transport ◽  
Transport Vesicles ◽  
Cargo Protein

Sec13p has been thought to be an essential component of the COPII coat, required for exit of proteins from the yeast endoplasmic reticulum (ER). We show herein that normal function of Sec13p was not required for ER exit of the Hsp150 glycoprotein. Hsp150 was secreted to the medium under restrictive conditions in a sec13-1mutant. The COPII components Sec23p and Sec31p and the GTP/GDP exchange factor Sec12p were required in functional form for secretion of Hsp150. Hsp150 leaves the ER in the absence of retrograde COPI traffic, and the responsible determinant is a peptide repeated 11 times in the middle of the Hsp150 sequence. Herein, we localized the sorting determinant for Sec13p-independent ER exit to the C-terminal domain. Sec13p-dependent invertase left the ER in the absence of normal Sec13p function, when fused to the C-terminal domain of Hsp150, demonstrating that this domain contained an active mediator of Sec13p-independent secretion. Thus, Hsp150 harbors two different signatures that regulate its ER exit. Our data show that transport vesicles lacking functional Sec13p can carry out ER-to-Golgi transport, but select only specific cargo protein(s) for ER exit.

scholarly journals Disruption of endoplasmic reticulum to Golgi transport leads to the accumulation of large aggregates containing beta-COP in pancreatic acinar cells.

1993 ◽  
Vol 4 (4) ◽  
pp. 413-424 ◽  
Author(s):  
L C Hendricks ◽  
M McCaffery ◽  
G E Palade ◽  
M G Farquhar
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Brefeldin A ◽  
Acinar Cells ◽  
Atp Depletion ◽  
Pancreatic Acinar Cells ◽  
Coat Proteins ◽  
Golgi Membranes ◽  
Golgi Transport ◽  
Transport Vesicles

When transport between the rough endoplasmic reticulum (ER) and Golgi complex is blocked by Brefeldin A (BFA) treatment or ATP depletion, the Golgi apparatus and associated transport vesicles undergo a dramatic reorganization. Because recent studies suggest that coat proteins such as beta-COP play an important role in the maintenance of the Golgi complex, we have used immunocytochemistry to determine the distribution of beta-COP in pancreatic acinar cells (PAC) in which ER to Golgi transport was blocked by BFA treatment or ATP depletion. In controls, beta-COP was associated with Golgi cisternae and transport vesicles as expected. Upon BFA treatment, PAC Golgi cisternae are dismantled and replaced by clusters of remnant vesicles surrounded by typical ER transitional elements that are generally assumed to represent the exit site of vesicular carriers for ER to Golgi transport. In BFA-treated PAC, beta-COP was concentrated in large (0.5-1.0 micron) aggregates closely associated with remnant Golgi membranes. In addition to typical ER transitional elements, we detected a new type of transitional element that consists of specialized regions of rough ER (RER) with ribosome-free ends that touched or extended into the beta-COP containing aggregates. In ATP-depleted PAC, beta-COP was not detected on Golgi membranes but was concentrated in similar large aggregates found on the cis side of the Golgi stacks. The data indicate that upon arrest of ER to Golgi transport by either BFA treatment or energy depletion, beta-COP dissociates from PAC Golgi membranes and accumulates as large aggregates closely associated with specialized ER elements. The latter may correspond to either the site of entry or exit for vesicles recycling between the Golgi and the RER.

scholarly journals RINT-1 Regulates the Localization and Entry of ZW10 to the Syntaxin 18 Complex

2006 ◽  
Vol 17 (6) ◽  
pp. 2780-2788 ◽  
Author(s):  
Kohei Arasaki ◽  
May Taniguchi ◽  
Katsuko Tani ◽  
Mitsuo Tagaya
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Trafficking ◽  
Protein Transport ◽  
Snare Complex ◽  
Checkpoint Control ◽  
Interacting Protein ◽  
Golgi Transport ◽  
Radiation Induced ◽  
And Function

RINT-1 was first identified as a Rad50-interacting protein that participates in radiation-induced G2/M checkpoint control. We have recently reported that RINT-1, together with the dynamitin-interacting protein ZW10 and others, is associated with syntaxin 18, an endoplasmic reticulum (ER)-localized SNARE involved in membrane trafficking between the ER and Golgi. To address the role of RINT-1 in membrane trafficking, we examined the effects of overexpression and knockdown of RINT-1 on Golgi morphology and protein transport from the ER. Overexpression of the N-terminal region of RINT-1, which is responsible for the interaction with ZW10, caused redistribution of ZW10. Concomitantly, ER-to-Golgi transport was blocked and the Golgi was dispersed. Knockdown of RINT-1 also disrupted membrane trafficking between the ER and Golgi. Notably, silencing of RINT-1 resulted in a reduction in the amount of ZW10 associated with syntaxin 18, concomitant with ZW10 redistribution. In contrast, no redistribution or release of RINT-1 from the syntaxin 18 complex was observed when ZW10 expression was reduced. These results taken together suggest that RINT-1 coordinates the localization and function of ZW10 by serving as a link between ZW10 and the SNARE complex comprising syntaxin 18.

scholarly journals Golgi Enzymes Are Enriched in Perforated Zones of Golgi Cisternae but Are Depleted in COPI Vesicles

2004 ◽  
Vol 15 (10) ◽  
pp. 4710-4724 ◽  
Author(s):  
Hee-Seok Kweon ◽  
Galina V. Beznoussenko ◽  
Massimo Micaroni ◽  
Roman S. Polishchuk ◽  
Alvar Trucco ◽  
...  
Keyword(s):  
Golgi Complex ◽  
Three Dimensional ◽  
Retrograde Transport ◽  
Cell Types ◽  
Free System ◽  
Progression Model ◽  
Golgi Transport ◽  
A Cell ◽  
Different Cell Types

In the most widely accepted version of the cisternal maturation/progression model of intra-Golgi transport, the polarity of the Golgi complex is maintained by retrograde transport of Golgi enzymes in COPI-coated vesicles. By analyzing enzyme localization in relation to the three-dimensional ultrastructure of the Golgi complex, we now observe that Golgi enzymes are depleted in COPI-coated buds and 50- to 60-nm COPI-dependent vesicles in a variety of different cell types. Instead, we find that Golgi enzymes are concentrated in the perforated zones of cisternal rims both in vivo and in a cell-free system. This lateral segregation of Golgi enzymes is detectable in some stacks during steady-state transport, but it was significantly prominent after blocking endoplasmic reticulum-to-Golgi transport. Delivery of transport carriers to the Golgi after the release of a transport block leads to a diminution in Golgi enzyme concentrations in perforated zones of cisternae. The exclusion of Golgi enzymes from COPI vesicles and their transport-dependent accumulation in perforated zones argues against the current vesicle-mediated version of the cisternal maturation/progression model.

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 Tubular ERGIC (t-ERGIC): a SURF4-mediated expressway for ER-to-Golgi transport

2021 ◽  
Author(s):  
Rui Yan ◽  
Kun Chen ◽  
Ke Xu
Keyword(s):  
Protein Trafficking ◽  
Volume Ratio ◽  
Retrograde Transport ◽  
Small Gtpase ◽  
Fine Tuning ◽  
En Bloc ◽  
Golgi Transport ◽  
Receptor Interactions ◽  
Cargo Receptor ◽  
Intermediate Compartment

The endoplasmic reticulum (ER)-to-Golgi transport is critical to protein secretion and intracellular sorting. Cargo carriers mediating the ER-to-Golgi transport are morphologically diverse, but it remains unclear whether this diversity arises from different cargo receptors, or whether it could lead to differential transport kinetics. Here we report a tubular ER-Golgi intermediate compartment (t-ERGIC) that is induced by the cargo receptor SURF4 and selectively expedites the ER-to-Golgi transport of SURF4 cargoes. Lacking the canonical ERGIC marker ERGIC-53 yet positive for the small GTPase Rab1, the t-ERGIC is further distinct from the stereotypical vesiculo-tubular cluster (VTC) ERGIC by its extremely elongated shape (~10 um long with <30 nm diameter). With its exceptional surface-to-volume ratio and en bloc cargo packaging, high (~2 um/s) intracellular traveling speeds, and ER-Golgi recycling capability, the t-ERGIC provides an efficient means for trafficking SURF4-bound cargoes. The biogenesis and cargo selectivity of t-ERGIC both depend on SURF4, which recognizes the N-terminus of soluble cargoes and co-clusters with the selected cargoes to expand the ER exit site. At the steady state, the t-ERGIC-mediated fast ER-to-Golgi transport is antagonized by retrograde transport based on the cargo C-terminal ER retrieval signal: we thus demonstrate the fine-tuning of protein trafficking and localization via its primary structure. Together, our results argue that specific cargo-receptor interactions give rise to distinct transport carriers, which in turn regulate the ER-to-Golgi trafficking kinetics.

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