Many proteins are associated with intracellular membranes due to their N-terminal myristoylation. Not all myristoylated proteins have the same localization within cells, indicating that other factors must determine their membrane targeting. The NCS (neuronal calcium sensor) proteins are a family of Ca2+-binding proteins with diverse functions. Most members of the family are N-terminally myristoylated and are either constitutively membrane-bound or have a Ca2+/myristoyl switch that allows their reversible membrane association in response to Ca2+ signals. In the case of hippocalcin and NCS-1, or alternatively KChIP1 (K+ channel-interacting protein 1), their N-terminal myristoylation motifs are sufficient for targeting to distinct organelles. We have shown that an N-terminal myristoylated hippocalcin peptide is able to specifically reproduce the membrane targeting of hippocalcin/NCS-1 when introduced into permeabilized cells. The peptide binds to liposomes containing phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] with high affinity (Kd 50 nM). Full-length hippocalcin also bound preferentially to liposomes supplemented with PtdIns(4,5)P2. Co-expression of hippocalcin-(1–14)–ECFP (enhanced cyan fluorescent protein) or NCS-1–ECFP partially displaced the expressed PH (pleckstrin homology) domain of phospholipase δ1 from the plasma membrane in live cells, indicating that they have a higher affinity for PtdIns(4,5)P2 than does this PH domain. The Golgi localization of the PH domain of FAPP1 (four-phosphate-adaptor protein 1), which binds to phosphatidylinositol 4-phosphate, was unaffected. The localization of NCS-1 and hippocalcin is likely to be determined, therefore, by their interaction with PtdIns(4,5)P2.
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Research Article|
October 10 2005
High-affinity interaction of the N-terminal myristoylation motif of the neuronal calcium sensor protein hippocalcin with phosphatidylinositol 4,5-bisphosphate
Dermott W. O'Callaghan;
Dermott W. O'Callaghan
1
1The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K.
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Lee P. Haynes;
Lee P. Haynes
1
1The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K.
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Robert D. Burgoyne
Robert D. Burgoyne
2
1The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K.
2To whom correspondence should be addressed (email burgoyne@liv.ac.uk).
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Publisher: Portland Press Ltd
Received:
June 23 2005
Revision Received:
July 29 2005
Accepted:
July 29 2005
Accepted Manuscript online:
July 29 2005
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London
2005
Biochem J (2005) 391 (2): 231–238.
Article history
Received:
June 23 2005
Revision Received:
July 29 2005
Accepted:
July 29 2005
Accepted Manuscript online:
July 29 2005
Citation
Dermott W. O'Callaghan, Lee P. Haynes, Robert D. Burgoyne; High-affinity interaction of the N-terminal myristoylation motif of the neuronal calcium sensor protein hippocalcin with phosphatidylinositol 4,5-bisphosphate. Biochem J 15 October 2005; 391 (2): 231–238. doi: https://doi.org/10.1042/BJ20051001
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