PITPs (phosphatidylinositol transfer proteins) are characterized by the presence of the PITP domain whose biochemical properties of binding and transferring PI (phosphatidylinositol) are well studied. Despite their wide-spread expression in both unicellular and multicellular organisms, they remain functionally uncharacterized. An emerging theme is that individual PITPs play highly specific roles in either membrane trafficking or signal transduction. To identify specific roles for PITPs, identification of interacting molecules would shed light on their molecular function. In the present paper, we describe binding partners for the class IIB PITP RdgBβ (retinal degeneration type Bβ). RdgBβ is a soluble PITP but is unique in that it contains a region of disorder at its C-terminus following its defining N-terminal PITP domain. The C-terminus of RdgBβ is phosphorylated at two serine residues, Ser274 and Ser299, which form a docking site for 14-3-3 proteins. Binding to 14-3-3 proteins protects RdgBβ from degradation that occurs at the proteasome after ubiquitination. In addition to binding 14-3-3, the PITP domain of RdgBβ interacts with the Ang II (angiotensin II)-associated protein ATRAP (Ang II receptor-associated protein). ATRAP is also an interacting partner for the AT1R (Ang II type 1 receptor). We present a model whereby RdgBβ functions by being recruited to the membrane by ATRAP and release of 14-3-3 from the C-terminus allows the disordered region to bind a second membrane to create a membrane bridge for lipid transfer, possibly under the control of Ang II.
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Conference Article|
March 21 2012
14-3-3 protein and ATRAP bind to the soluble class IIB phosphatidylinositol transfer protein RdgBβ at distinct sites
Shamshad Cockcroft;
Shamshad Cockcroft
1
1Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6JJ, U.K.
1To whom correspondence should be addressed (emails.cockcroft@ucl.ac.uk).
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Kathryn Garner
Kathryn Garner
1Department 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:
December 20 2011
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© The Authors Journal compilation © 2012 Biochemical Society
2012
Biochem Soc Trans (2012) 40 (2): 451–456.
Article history
Received:
December 20 2011
Citation
Shamshad Cockcroft, Kathryn Garner; 14-3-3 protein and ATRAP bind to the soluble class IIB phosphatidylinositol transfer protein RdgBβ at distinct sites. Biochem Soc Trans 1 April 2012; 40 (2): 451–456. doi: https://doi.org/10.1042/BST20110770
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