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Title | Molecular Basis for Membrane Recruitment by the PX and C2 Domains of Class II Phosphoinositide 3-Kinase-C2α. |
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Journal, issue, pages | Structure, Vol. 26, Issue 12, Page 1612-11625.e4, Year 2018 |
Publish date | Dec 4, 2018 |
Authors | Kai-En Chen / Vikas A Tillu / Mintu Chandra / Brett M Collins / |
PubMed Abstract | Phosphorylation of phosphoinositides by the class II phosphatidylinositol 3-kinase (PI3K) PI3K-C2α is essential for many processes, including neuroexocytosis and formation of clathrin-coated ...Phosphorylation of phosphoinositides by the class II phosphatidylinositol 3-kinase (PI3K) PI3K-C2α is essential for many processes, including neuroexocytosis and formation of clathrin-coated vesicles. A defining feature of the class II PI3Ks is a C-terminal module composed of phox-homology (PX) and C2 membrane interacting domains; however, the mechanisms that control their specific cellular localization remain poorly understood. Here we report the crystal structure of the C2 domain of PI3K-C2α in complex with the phosphoinositide head-group mimic inositol hexaphosphate, revealing two distinct pockets for membrane binding. The C2 domain preferentially binds to phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol (3,4,5)-trisphosphate, and low-resolution structures of the combined PX-C2 module by small-angle X-ray scattering reveal a compact conformation in which cooperative lipid binding by each domain binding can occur. Finally, we demonstrate an unexpected role for calcium in perturbing the membrane interactions of the PX-C2 module, which we speculate may be important for regulating the activity of PI3K-C2α. |
External links | Structure / PubMed:30293811 |
Methods | SAS (X-ray synchrotron) / X-ray diffraction |
Resolution | 1.678 - 2.604 Å |
Structure data | SASDD66: SASDD76: PDB-6bty: PDB-6btz: PDB-6bu0: PDB-6bub: |
Chemicals | ChemComp-O4B: ChemComp-HOH: ChemComp-SO4: ChemComp-GOL: ChemComp-FMT: ChemComp-IHP: |
Source |
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Keywords | TRANSFERASE / C2 domain / lipid binding / phosphoinositide / PI3-kinase / PX domain |