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| Subject Categories: Structural Biology | Signal Transduction |
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| The EMBO Journal
(2004) 23, 3711–3720, doi:10.1038/sj.emboj.7600388 Published online 9 September 2004 |
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| Structural determinants of phosphoinositide selectivity in splice variants of Grp1 family PH domains |
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| Thomas C Cronin, Jonathan P DiNitto, Michael P Czech and David G Lambright |
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Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA To whom correspondence should be addressed David G Lambright, Program in Molecular Medicine, University of Massachusetts Medical School, Two Biotech, 373 Plantation Street, Worcester, MA 01605, USA. Tel.: +1 508 856 6876; Fax: +1 508 856 4289; E-mail: David.Lambright@umassmed.edu Received 15 March 2004; Accepted 6 August 2004; Published online 9 September 2004. |
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| Abstract |
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The pleckstrin homology (PH) domains of the homologous proteins Grp1 (general receptor for phosphoinositides), ARNO (Arf nucleotide binding site opener), and Cytohesin-1 bind phosphatidylinositol (PtdIns) 3,4,5-trisphosphate with unusually high selectivity. Remarkably, splice variants that differ only by the insertion of a single glycine residue in the  1/2 loop exhibit dual specificity for PtdIns(3,4,5)P3 and PtdIns(4,5)P2. The structural basis for this dramatic specificity switch is not apparent from the known modes of phosphoinositide recognition. Here, we report crystal structures for dual specificity variants of the Grp1 and ARNO PH domains in either the unliganded form or in complex with the head groups of PtdIns(4,5)P2 and PtdIns(3,4,5)P3. Loss of contacts with the 1/2 loop with no significant change in head group orientation accounts for the significant decrease in PtdIns(3,4,5)P3 affinity observed for the dual specificity variants. Conversely, a small increase rather than decrease in affinity for PtdIns(4,5)P2 is explained by a novel binding mode, in which the glycine insertion alleviates unfavorable interactions with the 1/2 loop. These observations are supported by a systematic mutational analysis of the determinants of phosphoinositide recognition. |
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| Keywords: ARNO, Cytohesin-1, Grp1, pleckstrin homology domain, phosphoinositide |
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Top of page MORE ARTICLES LIKE THISThese links to content published by NPG are automatically generated RESEARCHCrystal structure of human osteoclast cathepsin K complex with E-64 Nature Structural Biology Correspondence (01 Feb 1997) Is the nitric oxide system involved in genetic hypertension in Dahl rats? Kidney International Original Article Structural insights into the regulation of PDK1 by phosphoinositides and inositol phosphates The EMBO Journal Article (13 Oct 2004) The EMBO Journal Article (15 Sep 1998) |
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