Phosphatidylinositol (PI) is the precursor lipid for the synthesis of PI 4,5-bisphosphate [PI(4,5)P2] at the plasma membrane (PM) and is sequentially phosphorylated by the lipid kinases, PI 4-kinase and phosphatidylinositol 4-phosphate (PI4P)-5-kinase. Receptor-mediated hydrolysis of PI(4,5)P2 takes place at the PM but PI resynthesis occurs at the endoplasmic reticulum (ER). Thus PI(4,5)P2 resynthesis requires the reciprocal transport of two key intermediates, phosphatidic acid (PA) and PI between the ER and the PM. PI transfer proteins (PITPs), defined by the presence of the PITP domain, can facilitate lipid transfer between membranes; the PITP domain comprises a hydrophobic cavity with dual specificity but accommodates a single phospholipid molecule. The class II PITP, retinal degeneration type B (RdgB)α is a multi-domain protein and its PITP domain can bind and transfer PI and PA. In Drosophila photoreceptors, a well-defined G-protein-coupled phospholipase Cβ (PLCβ) signalling pathway, phototransduction defects resulting from loss of RdgBα can be rescued by expression of the PITP domain provided it is competent for both PI and PA transfer. We propose that RdgBα proteins maintain PI(4,5)P2 homoeostasis after PLC activation by facilitating the reciprocal transport of PA and PI at ER–PM membrane contact sites.
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Scanning electron micrograph of a cell from the endosperm of a barley grain. The cell is tightly packed with large, disk-shaped (A-type) and much smaller, almost spherical (B-type) starch granules. The smooth areas in this image are the surface of the cell walls of neighbouring endosperm cells. For further details see pp. 157-163. Image kindly provided by Elaine Barclay and Vasilios Andriotis (John Innes Centre, Norwich). - PDF Icon PDF LinkTable of Contents
Review Article|
February 09 2016
RdgBα reciprocally transfers PA and PI at ER–PM contact sites to maintain PI(4,5)P2 homoeostasis during phospholipase C signalling in Drosophila photoreceptors
Shamshad Cockcroft;
Shamshad Cockcroft
1
*Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6JJ, U.K.
1To whom correspondence should be addressed (email s.cockcroft@ucl.ac.uk).
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Kathryn Garner;
Kathryn Garner
*Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6JJ, U.K.
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Shweta Yadav;
Shweta Yadav
*Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6JJ, U.K.
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Evelyn Gomez-Espinoza;
Evelyn Gomez-Espinoza
*Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6JJ, U.K.
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Padinjat Raghu
Padinjat Raghu
*Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6JJ, U.K.
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Publisher: Portland Press Ltd
Received:
November 25 2015
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2016 Authors; published by Portland Press Limited
2016
Biochem Soc Trans (2016) 44 (1): 286–292.
Article history
Received:
November 25 2015
Citation
Shamshad Cockcroft, Kathryn Garner, Shweta Yadav, Evelyn Gomez-Espinoza, Padinjat Raghu; RdgBα reciprocally transfers PA and PI at ER–PM contact sites to maintain PI(4,5)P2 homoeostasis during phospholipase C signalling in Drosophila photoreceptors. Biochem Soc Trans 15 February 2016; 44 (1): 286–292. doi: https://doi.org/10.1042/BST20150228
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