scholarly journals Neurobeachin, a protein implicated in membrane protein traffic and autism, is required for the formation and functioning of central synapses

2009 ◽  
Vol 587 (21) ◽  
pp. 5095-5106 ◽  
Author(s):  
Lucian Medrihan ◽  
Astrid Rohlmann ◽  
Richard Fairless ◽  
Johanna Andrae ◽  
Markus Döring ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Protein Traffic ◽  
Central Synapses

Lectins and protein traffic early in the secretory pathway

2002 ◽  
Vol 69 ◽  
pp. 73-82 ◽  
Author(s):  
Hans-Peter Hauri ◽  
Oliver Nufer ◽  
Lionel Breuza ◽  
Houchaima Ben Tekaya ◽  
Lu Liang
Keyword(s):  
Membrane Protein ◽  
Secretory Pathway ◽  
Integral Membrane Protein ◽  
Type I ◽  
Coat Proteins ◽  
Protein Traffic ◽  
Early Secretory Pathway ◽  
Er Export ◽  
Different Characteristics ◽  
Related Proteins

Lectins of the early secretory pathway are involved in selective transport of newly synthesized glycoproteins from the endoplasmic reticulum (ER) to the ER–Golgi intermediate compartment (ERGIC). The most prominent cycling lectin is the mannose-binding type I membrane protein ERGIC-53 (ERGIC protein of 53 kDa), a marker for the ERGIC, which functions as a cargo receptor to facilitate export of an increasing number of glycoproteins with different characteristics from the ER. Two ERGIC-53-related proteins, VIP36 (vesicular integral membrane protein 36) and a novel ERGIC-53-like protein, ERGL, are also found in the early secretory pathway. ERGL may act as a regulator of ERGIC-53. Studies of ERGIC-53 continue to provide new insights into the organization and dynamics of the early secretory pathway. Analysis of the cycling of ERGIC-53 uncovered a complex interplay of trafficking signals and revealed novel cytoplasmic ER-export motifs that interact with COP-II coat proteins. These motifs are common to type I and polytopic membrane proteins including presenilin 1 and presenilin 2. The results support the notion that protein export from the ER is selective.

scholarly journals The phosphatidylinositol 3-phosphate-binding protein SNX4 controls ATG9A recycling and autophagy

2021 ◽  
Vol 134 (3) ◽  
pp. jcs250670 ◽  
Author(s):  
Anthony Ravussin ◽  
Andreas Brech ◽  
Sharon A. Tooze ◽  
Harald Stenmark
Keyword(s):  
Membrane Protein ◽  
Autophagic Flux ◽  
Dependent Manner ◽  
Phosphate Binding ◽  
Protein Traffic ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Phosphate Binding Protein ◽  
Golgi Network ◽  
Phosphatidylinositol 3

ABSTRACTLate endosomes and lysosomes (endolysosomes) receive proteins and cargo from the secretory, endocytic and autophagic pathways. Although these pathways and the degradative processes of endolysosomes are well characterized, less is understood about protein traffic from these organelles. In this study, we demonstrate the direct involvement of the phosphatidylinositol 3-phosphate (PI3P)-binding SNX4 protein in membrane protein recycling from endolysosomes, and show that SNX4 is required for proper autophagic flux. We show that SNX4 mediates recycling of the lipid scramblase ATG9A, which drives expansion of nascent autophagosome membranes, from endolysosomes to early endosomes, from where ATG9A is recycled to the trans-Golgi network in a retromer-dependent manner. Upon siRNA-mediated depletion of SNX4 or the retromer component VPS35, we observed accumulation of ATG9A on endolysosomes and early endosomes, respectively. Moreover, starvation-induced autophagosome biogenesis and autophagic flux were inhibited when SNX4 was downregulated. We propose that proper ATG9A recycling by SNX4 sustains autophagy by preventing exhaustion of the available ATG9A pool.This article has an associated First Person interview with the first author of the paper.

scholarly journals The phosphatidylinositol 3-phosphate binding protein SNX4 controls ATG9A recycling and autophagy

2020 ◽  
Author(s):  
Anthony Ravussin ◽  
Sharon A. Tooze ◽  
Harald Stenmark
Keyword(s):  
Membrane Protein ◽  
Autophagic Flux ◽  
Dependent Manner ◽  
Phosphate Binding ◽  
Protein Traffic ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Phosphate Binding Protein ◽  
Golgi Network ◽  
Phosphatidylinositol 3

AbstractLate endosomes and lysosomes (endolysosomes) receive proteins and cargo from the secretory, endocytic and autophagic pathways. Whereas these pathways and the degradative processes of endolysosomes are well characterized, less is understood about protein traffic from these organelles. In this study, we demonstrate the direct involvement of the phosphatidylinositol 3-phosphate (PI3P) binding SNX4 protein in membrane protein recycling from endolysosomes, and show that SNX4 is required for proper autophagic flux. We show that SNX4 mediates recycling of the transmembrane autophagy machinery protein ATG9A from endolysosomes to early endosomes, from where ATG9A is recycled to the trans-Golgi network in a retromer-dependent manner. Upon siRNA-mediated depletion of SNX4 or the retromer component VPS35, we observed accumulation of ATG9A on endolysosomes and early endosomes, respectively. Moreover, starvation-induced autophagosome biogenesis and autophagic flux were inhibited when SNX4 was downregulated. Altogether, we propose that proper ATG9A recycling by SNX4 sustains autophagy by preventing exhaustion of the available ATG9A pool.

scholarly journals A Novel Casein Kinase 2 α-Subunit Regulates Membrane Protein Traffic in the Human Hepatoma Cell Line HuH-7

2000 ◽  
Vol 276 (3) ◽  
pp. 2075-2082 ◽  
Author(s):  
Xiaoying Shi ◽  
Barry Potvin ◽  
Tianmin Huang ◽  
Philip Hilgard ◽  
David C. Spray ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Cell Line ◽  
Hepatoma Cell ◽  
Casein Kinase ◽  
Hepatoma Cell Line ◽  
Human Hepatoma ◽  
Human Hepatoma Cell ◽  
Α Subunit ◽  
Protein Traffic ◽  
Human Hepatoma Cell Line

scholarly journals The AP-1 complex is essential for fungal growth via its role in secretory vesicle polar sorting, endosomal recycling and cytoskeleton organization

2018 ◽  
Author(s):  
Olga Martzoukou ◽  
George Diallinas ◽  
Sotiris Amillis
Keyword(s):  
Plasma Membrane ◽  
Membrane Protein ◽  
Fungal Growth ◽  
Secretory Vesicle ◽  
Secretory Vesicles ◽  
Protein Traffic ◽  
Cytoskeleton Organization ◽  
Endosomal Recycling ◽  
Specific Membrane

AbstractThe AP-1 complex is essential for membrane protein traffic via its role in the pinching-off and sorting of secretory vesicles from the trans-Golgi and/or endosomes. While its essentiality is undisputed in metazoa, its role in model simpler eukaryotes seems less clear. Here we dissect the role of AP-1 in the filamentous fungus Aspergillus nidulans and show that it is absolutely essential for growth due to its role in clathrin-dependent maintenance of polar traffic of specific membrane cargoes towards the apex of growing hyphae. We provide evidence that AP-1 is involved in both anterograde sorting of RabERab11-labeled secretory vesicles and RabA/BRab5- dependent endosome recycling. Additionally, AP-1 is shown to be critical for microtubule and septin organization, further rationalizing its essentiality in cells that face the challenge of cytoskeleton-dependent polarized cargo traffic. This work also opens a novel issue on how non-polar cargoes, such as transporters, are sorted to the eukaryotic plasma membrane.

TMCC3 localizes at the three-way junctions for the proper tubular network of the endoplasmic reticulum

2019 ◽  
Vol 476 (21) ◽  
pp. 3241-3260
Author(s):  
Sindhu Wisesa ◽  
Yasunori Yamamoto ◽  
Toshiaki Sakisaka
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Mammalian Cells ◽  
Coiled Coil ◽  
Transmembrane Domains ◽  
Domain Family ◽  
Coiled Coil Domain ◽  
U2os Cells ◽  
Er Membrane

The tubular network of the endoplasmic reticulum (ER) is formed by connecting ER tubules through three-way junctions. Two classes of the conserved ER membrane proteins, atlastins and lunapark, have been shown to reside at the three-way junctions so far and be involved in the generation and stabilization of the three-way junctions. In this study, we report TMCC3 (transmembrane and coiled-coil domain family 3), a member of the TEX28 family, as another ER membrane protein that resides at the three-way junctions in mammalian cells. When the TEX28 family members were transfected into U2OS cells, TMCC3 specifically localized at the three-way junctions in the peripheral ER. TMCC3 bound to atlastins through the C-terminal transmembrane domains. A TMCC3 mutant lacking the N-terminal coiled-coil domain abolished localization to the three-way junctions, suggesting that TMCC3 localized independently of binding to atlastins. TMCC3 knockdown caused a decrease in the number of three-way junctions and expansion of ER sheets, leading to a reduction of the tubular ER network in U2OS cells. The TMCC3 knockdown phenotype was partially rescued by the overexpression of atlastin-2, suggesting that TMCC3 knockdown would decrease the activity of atlastins. These results indicate that TMCC3 localizes at the three-way junctions for the proper tubular ER network.

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