Essential role of Ca2+/calmodulin in Early Endosome Antigen-1 localization
Authors
Lawe, Deirdre C.Sitouah, Nachida
Hayes, Susan
Chawla, Anil
Virbasius, Joseph V.
Tuft, Richard A.
Fogarty, Kevin E.
Lifshitz, Lawrence M.
Lambright, David G.
Corvera, Silvia
UMass Chan Affiliations
Department of PhysiologyProgram in Molecular Medicine
Graduate School of Biomedical Sciences
Document Type
Journal ArticlePublication Date
2003-07-15Keywords
1-Phosphatidylinositol 3-Kinase; Amino Acid Motifs; Animals; COS Cells; Calcium; Calmodulin; Cercopithecus aethiops; Endosomes; Liposomes; *Membrane Fusion; Membrane Proteins; Microscopy, Fluorescence; Mutation; Protein Structure, Quaternary; Recombinant Proteins; Sulfonamides; Vesicular Transport Proteins; rab5 GTP-Binding ProteinsLife Sciences
Medicine and Health Sciences
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Ca2+ is an essential requirement in membrane fusion, acting through binding proteins such as calmodulin (CaM). Ca2+/CaM is required for early endosome fusion in vitro, however, the molecular basis for this requirement is unknown. An additional requirement for endosome fusion is the protein Early Endosome Antigen 1 (EEA1), and its recruitment to the endosome depends on phosphatidylinositol 3-phosphate [PI(3)P] and the Rab5 GTPase. Herein, we demonstrate that inhibition of Ca2+/CaM, by using either chemical inhibitors or specific antibodies directed to CaM, results in a profound inhibition of EEA1 binding to endosomal membranes both in live cells and in vitro. The concentration of Ca2+/CaM inhibitors required for a full dissociation of EEA1 from endosomal membranes had no effect on the activity of phosphatidylinositol 3-kinases or on endogenous levels of PI(3)P. However, the interaction of EEA1 with liposomes containing PI(3)P was decreased by Ca2+/CaM inhibitors. Thus, Ca2+/CaM seems to be required for the stable interaction of EEA1 with endosomal PI(3)P, perhaps by directly or indirectly stabilizing the quaternary organization of the C-terminal FYVE domain of EEA1. This requirement is likely to underlie at least in part the essential role of Ca2+/CaM in endosome fusion.Source
Mol Biol Cell. 2003 Jul;14(7):2935-45. Epub 2003 Mar 20. Link to article on publisher's siteDOI
10.1091/mbc.E02-09-0591Permanent Link to this Item
http://hdl.handle.net/20.500.14038/33998PubMed ID
12857876Related Resources
Link to article in PubMedae974a485f413a2113503eed53cd6c53
10.1091/mbc.E02-09-0591
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