Nucleocytoplasmic shuttling of human inositol phosphate multikinase is influenced by CK2 phosphorylation
-
Rüdiger Meyer
,
Patrick Ehm
Abstract
Human inositol phosphate multikinase (IPMK) is a multifunctional protein in cellular signal transduction, namely, a multispecific inositol phosphate kinase, phosphatidylinositol 3-kinase, and a scaffold within the mTOR-raptor complex. To fulfill these nuclear and cytoplasmic functions, intracellular targeting of IPMK needs to be regulated. We show here that IPMK, which has been considered to be a preferentially nuclear protein, is a nucleocytoplasmic shuttling protein, whose nuclear export is mediated by classical nuclear export receptor CRM1. We identified a functional nuclear export signal (NES) additionally to its previously described nuclear import signal (NLS). Furthermore, we describe a mechanism by which the activity of the IPMK-NLS is controlled. Protein kinase CK2 binds endogenous IPMK and phosphorylates it at serine 284. Interestingly, this phosphorylation can decrease nuclear localization of IPMK cell type specifically. A controlled nuclear import of IPMK may direct its actions either toward nuclear inositol phosphate (InsPx) metabolism or cytoplasmic actions on InsPx, phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2], as well as mTOR-raptor.
©2012 by Walter de Gruyter Berlin Boston
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Articles in the same Issue
- Genes and Nucleic Acids
- The effect of cancer procoagulant on expression of metastatic and angiogenic markers in breast cancer and embryonic stem cell lines
- Characterization of RNA damage under oxidative stress in Escherichia coli
- Membranes, Lipids, Glycobiology
- Uncommon membrane distribution of Shiga toxin glycosphingolipid receptors in toxin-sensitive human glomerular microvascular endothelial cells
- Cell Biology and Signaling
- Nucleocytoplasmic shuttling of human inositol phosphate multikinase is influenced by CK2 phosphorylation
- Apolipoprotein A5 internalized by human adipocytes modulates cellular triglyceride content
- Mammalian carboxylesterase (CES) releases GPI-anchored proteins from the cell surface upon lipid raft fluidization
- Proteolysis
- Biochemical characterization and structural modeling of human cathepsin E variant 2 in comparison to the wild-type protein
- Novel Techniques
- A fluorescence correlation spectroscopy-based enzyme assay for human Dicer
- Development of a host blood meal database: de novo sequencing of hemoglobin from nine small mammals using mass spectrometry
- Prelims
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