Comparative phytohormone profiles, lipid kinase and lipid phosphatase activities in barley aleurone, coleoptile, and root tissues

2012 ◽  
Vol 58 ◽  
pp. 83-88 ◽  
Author(s):  
Maria V. Meringer ◽  
Ana L. Villasuso ◽  
Susana J. Pasquaré ◽  
Norma M. Giusto ◽  
Estela E. Machado ◽  
...  
Keyword(s):  
Lipid Kinase ◽  
Phosphatase Activities ◽  
Lipid Phosphatase ◽  
Barley Aleurone ◽  
Root Tissues

Investigating lipid signalling: it's all about finding the right PI

2008 ◽  
Vol 413 (1) ◽  
pp. e5-e6 ◽  
Author(s):  
Erik Nielsen
Keyword(s):  
Signal Transduction ◽  
Signal Transduction Pathways ◽  
Lipid Kinase ◽  
Phosphatase Activities ◽  
Cellular Signal Transduction ◽  
Lipid Signalling ◽  
Lipid Phosphatase ◽  
Biochemical Journal ◽  
Cellular Signal ◽  
The Right

Phosphoinositides are well-known components of cellular signal transduction pathways and, more recently, have been shown to play important roles in organelle identity and targeting determinants for various cytosolic proteins. Conversion of PtdIns into its various phosphorylated derivatives, such as PtdIns4P and PtdIns(4,5)P2, is accomplished by a series of distinct lipid kinase and lipid phosphatase activities that are localized to specific subcellular membranes. As a result, production of distinct PtdIns forms is thought to be largely dependent on the access of these enzymes to their PtdIns or PtdInsP substrates. Interestingly, an investigation of two different PIS (PtdIns synthase) isoforms by Lofke et al. in this issue of the Biochemical Journal now indicates that the ability of PtdIns to be converted into downstream PtdInsPs may depend upon the PIS isoform from which it was synthesized.

scholarly journals Assembly of a Fab1 Phosphoinositide Kinase Signaling Complex Requires the Fig4 Phosphoinositide Phosphatase

2008 ◽  
Vol 19 (10) ◽  
pp. 4273-4286 ◽  
Author(s):  
Roberto J. Botelho ◽  
Jem A. Efe ◽  
David Teis ◽  
Scott D. Emr
Keyword(s):  
Protein Complex ◽  
Functional Unit ◽  
Dual Function ◽  
Dual Roles ◽  
Lipid Kinase ◽  
Unknown Mechanism ◽  
Signaling Complex ◽  
Lipid Phosphatase ◽  
Phosphoinositide Phosphatase ◽  
Phosphoinositide Kinase

Phosphatidylinositol-3,5-bisphosphate [PtdIns(3,5)P2] regulates several vacuolar functions, including acidification, morphology, and membrane traffic. The lipid kinase Fab1 converts phosphatidylinositol-3-phosphate [PtdIns(3)P] to PtdIns(3,5)P2. PtdIns(3,5)P2levels are controlled by the adaptor-like protein Vac14 and the Fig4 PtdIns(3,5)P2-specific 5-phosphatase. Interestingly, Vac14 and Fig4 serve a dual function: they are both implicated in the synthesis and turnover of PtdIns(3,5)P2by an unknown mechanism. We now show that Fab1, through its chaperonin-like domain, binds to Vac14 and Fig4 and forms a vacuole-associated signaling complex. The Fab1 complex is tethered to the vacuole via an interaction between the FYVE domain in Fab1 and PtdIns(3)P on the vacuole. Moreover, Vac14 and Fig4 bind to each other directly and are mutually dependent for interaction with the Fab1 kinase. Our observations identify a protein complex that incorporates the antagonizing Fab1 lipid kinase and Fig4 lipid phosphatase into a common functional unit. We propose a model explaining the dual roles of Vac14 and Fig4 in the synthesis and turnover of PtdIns(3,5)P2.

scholarly journals Functional Characterization Of The VAC14 Self-Interaction Domain

2021 ◽  
Author(s):  
Tamadher A. Alghamdi
Keyword(s):  
Functional Characterization ◽  
Regulatory Protein ◽  
Adaptor Protein ◽  
Interaction Domain ◽  
Lipid Kinase ◽  
Lipid Phosphatase ◽  
C Terminus ◽  
Regulatory Complex ◽  
Steady State Levels ◽  
And Function

PtdIns(3,5)P2 is a low-abundance signaling lipid present at < 0.1 % of total PtdIns lipids in yeasts and mammals. Reduced levels of PtdIns(3,5)P2 contributes to neurodegenerative disorders in humans and vacuolar defects in yeasts. Steady-state levels of PtdIns(3,5)P2 are dependent on both its rate of synthesis and turnover. In yeast, PtdIns(3,5)P2 is produced on the vacuole membrane by phosphorylation of PtdIns(3)P at the 5 position of its inositol ring by the Fab1 lipid kinase. Cells lacking Fab1 make no PtdIns(3,5)P2 and exhibit defects in vacuole morphology and function. The lipid phosphatase Fig4 counteracts Fab1 activity by turnover of PtdIns(3,5)P2 into PtdIns(3)P. Vac14 is a regulatory protein implicated in the synthesis and turnover of PtdIns(3,5)P2. It acts as an adaptor protein that controls both of Fab1 and Fig4 proteins. In addition, Vac14 exists as a multimer that allows for self-interaction. However, multimerization state of Vac14 as well as the domain responsible for self-interaction remained unknown. This study aimed to identify the self-interaction domain to elucidate its role in the assembly of the regulatory complex of PtdIns(3,5)P2. The observations seen in this study suggested that Vac14 self-interacts via multiple conserved motifs in the C-terminus, which are crucial for interaction with Fab1 and Fig4, and the normal morphology of yeast vacuoles.

scholarly journals Roles for a lipid phosphatase in the activation of its opposing lipid kinase

2020 ◽  
Vol 31 (17) ◽  
pp. 1835-1845
Author(s):  
Bethany S. Strunk ◽  
Noah Steinfeld ◽  
Sora Lee ◽  
Natsuko Jin ◽  
Cecilia Muñoz-Rivera ◽  
...  
Keyword(s):  
Protein Complex ◽  
Dynamic Regulation ◽  
Lipid Kinase ◽  
Lipid Phosphatase ◽  
Phosphoinositide Phosphatase ◽  
Turn Over

The phosphoinositide phosphatase Fig4 is predicted to turn over the signaling lipid PI3,5P2. It is shown that a major role of Fig4 is to elevate PI3,5P2 via dynamic regulation of the protein complex that activates its opposing lipid kinase, Fab1.

scholarly journals Characterization of the Regulation and Function of Phosphatidylinositol 3,5-Bisphosphate

2021 ◽  
Author(s):  
Shannon Cheuk Ying Ho
Keyword(s):  
Membrane Trafficking ◽  
Adaptor Protein ◽  
Cellular Functions ◽  
Lipid Kinase ◽  
Cellular Processes ◽  
Lipid Phosphatase ◽  
Tooth Type ◽  
And Function ◽  
Endocytic Compartments ◽  
Lysosomal Acidification

PtdIns(3,5)P2 is a low abundance phosphoinositide that is involved in a variety of cellular processes. Most notably, PtdIns(3,5)P2 is known to regulate vacuolar/lysosomal morphology. Deficiency in PtdIns(3,5)P2 results in enlargement of the yeast vacuole and, an extensive vacuolation of the late endocytic compartments in higher eukaryotes (1, 2). In addition, PtdIns(3,5)P2 is also involved in cellular functions including membrane trafficking, autophagy, and vacuolar/lysosomal acidification. However, the current study provided evidence that shows that the vacuole/lysosomes of PtdIns(3,5)P2-deficient cells remain acidic. Hence, PtdIns(3,5)P2 may not have a role in steady-state vacuolar/lysosomal acidification. PtdIns(3,5)P2 is synthesized by the Fab1 lipid kinase and degraded by the antagonistic Fig4 lipid phosphatase. Vac14, an adaptor protein, is known to interact with both Fab1 and Fig4 to form a complex on the vacuolar membrane. This study demonstrated that Vac14 is required to form a homodimer for its interaction with Fig4 and Fab1. In addition, formation of the homodimer is necessary for regulation of PtdIns(3,5)P2. Mutations in human Vac14 and Fig4 has been identified in patients with neurodegenerative diseases, such as amyotrophic lateral sclerosis and Charcot-Marie-Tooth Type 4J (3, 4). This study provides an important stepping stone in characterizing the regulatory mechanism and understanding the function of PtdIns(3,5)P2

scholarly journals Characterization of the Regulation and Function of Phosphatidylinositol 3,5-Bisphosphate

2021 ◽  
Author(s):  
Shannon Cheuk Ying Ho
Keyword(s):  
Membrane Trafficking ◽  
Adaptor Protein ◽  
Cellular Functions ◽  
Lipid Kinase ◽  
Cellular Processes ◽  
Lipid Phosphatase ◽  
Tooth Type ◽  
And Function ◽  
Endocytic Compartments ◽  
Lysosomal Acidification

PtdIns(3,5)P2 is a low abundance phosphoinositide that is involved in a variety of cellular processes. Most notably, PtdIns(3,5)P2 is known to regulate vacuolar/lysosomal morphology. Deficiency in PtdIns(3,5)P2 results in enlargement of the yeast vacuole and, an extensive vacuolation of the late endocytic compartments in higher eukaryotes (1, 2). In addition, PtdIns(3,5)P2 is also involved in cellular functions including membrane trafficking, autophagy, and vacuolar/lysosomal acidification. However, the current study provided evidence that shows that the vacuole/lysosomes of PtdIns(3,5)P2-deficient cells remain acidic. Hence, PtdIns(3,5)P2 may not have a role in steady-state vacuolar/lysosomal acidification. PtdIns(3,5)P2 is synthesized by the Fab1 lipid kinase and degraded by the antagonistic Fig4 lipid phosphatase. Vac14, an adaptor protein, is known to interact with both Fab1 and Fig4 to form a complex on the vacuolar membrane. This study demonstrated that Vac14 is required to form a homodimer for its interaction with Fig4 and Fab1. In addition, formation of the homodimer is necessary for regulation of PtdIns(3,5)P2. Mutations in human Vac14 and Fig4 has been identified in patients with neurodegenerative diseases, such as amyotrophic lateral sclerosis and Charcot-Marie-Tooth Type 4J (3, 4). This study provides an important stepping stone in characterizing the regulatory mechanism and understanding the function of PtdIns(3,5)P2

scholarly journals Functional Characterization Of The VAC14 Self-Interaction Domain

2021 ◽  
Author(s):  
Tamadher A. Alghamdi
Keyword(s):  
Functional Characterization ◽  
Regulatory Protein ◽  
Adaptor Protein ◽  
Interaction Domain ◽  
Lipid Kinase ◽  
Lipid Phosphatase ◽  
C Terminus ◽  
Regulatory Complex ◽  
Steady State Levels ◽  
And Function

PtdIns(3,5)P2 is a low-abundance signaling lipid present at < 0.1 % of total PtdIns lipids in yeasts and mammals. Reduced levels of PtdIns(3,5)P2 contributes to neurodegenerative disorders in humans and vacuolar defects in yeasts. Steady-state levels of PtdIns(3,5)P2 are dependent on both its rate of synthesis and turnover. In yeast, PtdIns(3,5)P2 is produced on the vacuole membrane by phosphorylation of PtdIns(3)P at the 5 position of its inositol ring by the Fab1 lipid kinase. Cells lacking Fab1 make no PtdIns(3,5)P2 and exhibit defects in vacuole morphology and function. The lipid phosphatase Fig4 counteracts Fab1 activity by turnover of PtdIns(3,5)P2 into PtdIns(3)P. Vac14 is a regulatory protein implicated in the synthesis and turnover of PtdIns(3,5)P2. It acts as an adaptor protein that controls both of Fab1 and Fig4 proteins. In addition, Vac14 exists as a multimer that allows for self-interaction. However, multimerization state of Vac14 as well as the domain responsible for self-interaction remained unknown. This study aimed to identify the self-interaction domain to elucidate its role in the assembly of the regulatory complex of PtdIns(3,5)P2. The observations seen in this study suggested that Vac14 self-interacts via multiple conserved motifs in the C-terminus, which are crucial for interaction with Fab1 and Fig4, and the normal morphology of yeast vacuoles.

scholarly journals Determinants of the tumor suppressor INPP4B protein and lipid phosphatase activities

2013 ◽  
Vol 440 (2) ◽  
pp. 277-282 ◽  
Author(s):  
Sandra M. Lopez ◽  
Myles C. Hodgson ◽  
Charles Packianathan ◽  
Ozlem Bingol-Ozakpinar ◽  
Fikriye Uras ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Phosphatase Activities ◽  
Lipid Phosphatase

scholarly journals Characterizing the VAC14 multimeric state

2021 ◽  
Author(s):  
Shannon Cheuk Ying Ho
Keyword(s):  
Nervous System ◽  
Membrane Trafficking ◽  
Adaptor Protein ◽  
Lipid Kinase ◽  
Charcot Marie Tooth ◽  
Charcot Marie Tooth Disease ◽  
Cellular Processes ◽  
Lipid Phosphatase ◽  
Lateral Sclerosis ◽  
Tooth Disease

PtdIns(3,5)₂ is involved in a number of cellular processes, such as the regulation of endolysosome morphology and membrane trafficking, autophagy and ion transport. In mammala, PtdIns(3,5)₂ deficiency results in vacuolation most notable in the neurons of the central and peripheral nervous system. This can potentially block the trafficking of neurotransmitters leading to a progression of neurodegeneration diseases such as amyotrophic lateral sclerosis and Charcot-Marie-Tooth disease. PtdIns(3,5)₂ is synthesized by the Fab1/PIKfyve lipid kinase and degraded by the Fig4/Sac3 lipid phosphatase. Fab1 and Fig4 are found in a complex with its regulator, the Fac14/ArPIKfyve adaptor protein. The aim of this study was to identify the multimeric state of recombinant Vac14 in order to help elucidate the importance of the Vac14 multimer in the regulation of PtdIns(3,5)₂. The result of this study indicated that recombinant Vac14 forms a homodimer and/or homotrimer.

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