title: Split pleckstrin homology domain-mediated cytoplasmic-nuclear localization of PI3-kinase enhancer GTPase.
abstract: Cytoplasm-nucleus shuttling of phosphoinositol 3-kinase enhancer (PIKE) is known to correlate directly with its cellular functions. However, the molecular mechanism governing this shuttling is not known. In this work, we demonstrate that PIKE is a new member of split pleckstrin homology (PH) domain-containing proteins. The structure solved in this work reveals that the PIKE PH domain is split into halves by a positively charged nuclear localization sequence. The PIKE PH domain binds to the head groups of di- and triphosphoinositides with similar affinities. Lipid membrane binding of the PIKE PH domain is further enhanced by the positively charged nuclear localization sequence, which is juxtaposed to the phosphoinositide head group-binding pocket of the domain. We demonstrate that the cytoplasmic-nuclear shuttling of PIKE is dynamically regulated by the balancing actions of the lipid-binding property of both the split PH domain and the nuclear targeting function of its nuclear localization sequence.
authors: Department of Biochemistry, Molecular Neuroscience Center, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China.
authors: Jing
authors: J
authors: Yan
authors: Wenyu
authors: W
authors: Wen
authors: Ling-Nga
authors: LN
authors: Chan
authors: Mingjie
authors: M
authors: Zhang
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000201:enzymology*; D003593:Cytoplasm / Q000201:enzymology*; D004285:Dogs; D019204:GTP-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D009154:Mutation; D019913:Nuclear Localization Signals / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism*; D010750:Phosphoproteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport; D051381:Rats; D017386:Sequence Homology, Amino Acid
chemical_list: D001798:Blood Proteins; D020690:GTPase-Activating Proteins; D019913:Nuclear Localization Signals; D010716:Phosphatidylinositols; D010750:Phosphoproteins; C039077:platelet protein P47; C485997:AGAP2 protein, human; D019204:GTP-Binding Proteins