scholarly journals Apolipoprotein L9 interacts with LC3/GABARAP and is a microtubule-associated protein with a widespread subcellular distribution

2019 ◽  
Author(s):  
Arvind A. Thekkinghat ◽  
Kamlesh K. Yadav ◽  
Pundi N. Rangarajan
Keyword(s):  
Animal Cell ◽  
Binding Protein ◽  
Lipid Binding ◽  
Lipid Transport ◽  
Bafilomycin A1 ◽  
Transmembrane Region ◽  
Intracellular Lipid ◽  
Cellular Processes ◽  
Key Players ◽  
Summary Statement

AbstractMouse Apolipoprotein L9 is a 34-kDa phosphatidylethanolamine (PE)-binding protein. The gene is present only in mouse and rat genomes; hence it is taxonomically restricted. To understand why, it is essential to uncover details about its functions in cellular processes. Here we show that ApoL9 interacts with the proteins of the LC3 and GABARAP subfamilies, which are key players in macroautophagy. In amino-acid starved cells it preferentially interacts with lipidated LC3B, likely by binding to its PE moiety. On treatment with autophagy inhibitors bafilomycin A1 and chloroquine, ApoL9 is found near swollen mitochondria and on lysosomes/LAMP1-positive compartments. However, ApoL9 itself does not seem to be degraded as a result of autophagy, suggesting that it is not an autophagy cargo receptor. Deletions in a putative transmembrane region between amino acids 110 and 145 abolish PE-binding. In addition, ApoL9 can redistribute to stress granules, can homooligomerize, and is a microtubule-associated protein. In short, its distribution in the cell is quite widespread, suggesting that it could have functions at the intersection of membrane binding and reorganization, autophagy, cellular stress and intracellular lipid transport.Summary statementThis article is about how Apolipoprotein L9, a lipid-binding protein, has versatile properties and influences a variety of processes taking place inside an animal cell.

scholarly journals Structural insight into a partially unfolded state preceding aggregation in an intracellular lipid-binding protein

FEBS Journal ◽  
2017 ◽  
Author(s):  
Gergő Horváth ◽  
László Biczók ◽  
Zsuzsa Majer ◽  
Mihály Kovács ◽  
András Micsonai ◽  
...  
Keyword(s):  
Binding Protein ◽  
Lipid Binding ◽  
Intracellular Lipid ◽  
Lipid Binding Protein ◽  
Unfolded State ◽  
Structural Insight ◽  
Partially Unfolded ◽  
Insight Into

scholarly journals Poly(A) binding protein is required for mRNP remodeling to form P-bodies in mammalian cells

2021 ◽  
Author(s):  
Jingwei Xie ◽  
Yu Chen ◽  
Xiaoyu Wei ◽  
Guennadi Kozlov
Keyword(s):  
Mammalian Cells ◽  
Binding Protein ◽  
Stress Granules ◽  
Body Formation ◽  
P Bodies ◽  
Rna Granules ◽  
Cellular Processes ◽  
Early Stages ◽  
Summary Statement

AbstractCompartmentalization of mRNA through formation of RNA granules is involved in many cellular processes, yet it is not well understood. mRNP complexes undergo dramatic changes in protein compositions, reflected by markers of P-bodies and stress granules. Here, we show that PABPC1, albeit absent in P-bodies, plays important role in P-body formation. Depletion of PABPC1 decreases P-body population in unstressed cells. Upon stress in PABPC1 depleted cells, individual P-bodies fail to form and instead P-body proteins assemble on PABPC1-containing stress granules. We hypothesize that mRNP recruit proteins via PABPC1 to assemble P-bodies, before PABPC1 is displaced from mRNP. Further, we demonstrate that GW182 can mediate P-body assembly. These findings help us understand the early stages of mRNP remodeling and P-body formation.Summary statementA novel role of poly(A) binding protein is reported in P-body formation

scholarly journals A CD36-related Transmembrane Protein Is Coordinated with an Intracellular Lipid-binding Protein in Selective Carotenoid Transport for Cocoon Coloration

2010 ◽  
Vol 285 (10) ◽  
pp. 7739-7751 ◽  
Author(s):  
Takashi Sakudoh ◽  
Tetsuya Iizuka ◽  
Junko Narukawa ◽  
Hideki Sezutsu ◽  
Isao Kobayashi ◽  
...  
Keyword(s):  
Binding Protein ◽  
Transmembrane Protein ◽  
Lipid Binding ◽  
Intracellular Lipid ◽  
Lipid Binding Protein

scholarly journals Developmental and structural studies of an intracellular lipid binding protein expressed in the ileal epithelium.

1990 ◽  
Vol 265 (31) ◽  
pp. 19199-19207
Author(s):  
J.C. Sacchettini ◽  
S.M. Hauft ◽  
S.L. Van Camp ◽  
D.P. Cistola ◽  
J.I. Gordon
Keyword(s):  
Binding Protein ◽  
Lipid Binding ◽  
Structural Studies ◽  
Intracellular Lipid ◽  
Lipid Binding Protein

scholarly journals Tau, XMAP215/Msps and Eb1 jointly regulate microtubule polymerisation and bundle formation in axons

2020 ◽  
Author(s):  
Ines Hahn ◽  
Andre Voelzmann ◽  
Jill Parkin ◽  
Judith Fuelle ◽  
Paula G Slater ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Functional Unit ◽  
Axon Growth ◽  
Loss Of Function ◽  
Cellular Processes ◽  
Axon Development ◽  
Key Players ◽  
Summary Statement ◽  
High Age ◽  
Mutant Phenotypes

AbstractAxons are the enormously long cable-like cellular processes of neurons that wire nervous systems and have to survive for up to a century in humans. We lose ~40% of axons towards high age and far more in neurodegenerative diseases. Sustaining axons requires axonal transport and dynamic morphogenetic changes, both crucially dependent on bundles of microtubules that run all along axons. How polymerisation is regulated to form, repair and replace microtubules in these bundles during axon development and maintenance is virtually unknown. Here, we show in axons of Drosophila and Xenopus neurons alike that Eb1, XMAP215/Msps and Tau are key players which operate as one functional unit to promote microtubule polymerisation. Eb1 and XMAP215/Msps are interdependent core factors at the microtubule tip, whereas Tau outcompetes Eb1 binding at microtubule lattices, thus preventing its pool depletion at polymerising plus ends. In agreement with their closely interwoven functions, the three factors show the same combination of axonal loss-of-function mutant phenotypes including: (1) reduced microtubule polymerisation dynamics and shorter axon growth, indicating their importance for upholding microtubule mass in axons; (2) prominent deterioration of parallel microtubule bundles into disorganised curled conformations, indicating their key roles in promoting essential axonal architecture. We show the latter to occur through Eb1- and spectraplakin-dependent guidance of extending microtubules. We conclude that Eb1, XMAP215/Msps and Tau jointly promote microtubule polymerisation, important to regulate the quantity and bundled organisation of microtubules and offering new ways to think about developmental and degenerative axon pathologies and how to treat them.Summary statementEb1, XMAP215 and tau operate as a functional unit in axons to promote the polymerisation of microtubules and their organisation into the parallel bundles essential for axonal transport.

Evolution of the duplicated intracellular lipid-binding protein genes of teleost fishes

2017 ◽  
Vol 292 (4) ◽  
pp. 699-727 ◽  
Author(s):  
Ananda B. Venkatachalam ◽  
Manoj B. Parmar ◽  
Jonathan M. Wright
Keyword(s):  
Binding Protein ◽  
Lipid Binding ◽  
Teleost Fishes ◽  
Intracellular Lipid ◽  
Lipid Binding Protein

scholarly journals Molecular and cellular dissection of the oxysterol-binding protein cycle through a fluorescent inhibitor

2020 ◽  
Vol 295 (13) ◽  
pp. 4277-4288 ◽  
Author(s):  
Tiphaine Péresse ◽  
David Kovacs ◽  
Mélody Subra ◽  
Joëlle Bigay ◽  
Meng-Chen Tsai ◽  
...  
Keyword(s):  
Binding Protein ◽  
Lipid Binding ◽  
Lipid Transfer ◽  
Intracellular Lipid ◽  
Membrane Reconstitution ◽  
Bioactive Natural Products ◽  
Oxysterol Binding Protein ◽  
Binding Cavity ◽  
Phosphatidylinositol 4

ORPphilins are bioactive natural products that strongly and selectively inhibit the growth of some cancer cell lines and are proposed to target intracellular lipid-transfer proteins of the oxysterol-binding protein (OSBP) family. These conserved proteins exchange key lipids, such as cholesterol and phosphatidylinositol 4-phosphate (PI(4)P), between organelle membranes. Among ORPphilins, molecules of the schweinfurthin family interfere with intracellular lipid distribution and metabolism, but their functioning at the molecular level is poorly understood. We report here that cell line sensitivity to schweinfurthin G (SWG) is inversely proportional to cellular OSBP levels. By taking advantage of the intrinsic fluorescence of SWG, we followed its fate in cell cultures and show that its incorporation at the trans-Golgi network depends on cellular abundance of OSBP. Using in vitro membrane reconstitution systems and cellular imaging approaches, we also report that SWG inhibits specifically the lipid transfer activity of OSBP. As a consequence, post-Golgi trafficking, membrane cholesterol levels, and PI(4)P turnover were affected. Finally, using intermolecular FRET analysis, we demonstrate that SWG directly binds to the lipid-binding cavity of OSBP. Collectively these results describe SWG as a specific and intrinsically fluorescent pharmacological tool for dissecting OSBP properties at the cellular and molecular levels. Our findings indicate that SWG binds OSBP with nanomolar affinity, that this binding is sensitive to the membrane environment, and that SWG inhibits the OSBP-catalyzed lipid exchange cycle.

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