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Mol Biol Cell. 2003 Feb;14(2):625-41.

EpsinR: an ENTH domain-containing protein that interacts with AP-1.

Author information

  • 1University of Cambridge, Department of Clinical Biochemistry, Cambridge Institute for Medical Research, United Kingdom.

Erratum in

  • Mol Biol Cell. 2003 Apr;14(4):following 1743.

Abstract

We have used GST pulldowns from A431 cell cytosol to identify three new binding partners for the gamma-adaptin appendage: Snx9, ARF GAP1, and a novel ENTH domain-containing protein, epsinR. EpsinR is a highly conserved protein that colocalizes with AP-1 and is enriched in purified clathrin-coated vesicles. However, it does not require AP-1 to get onto membranes and remains membrane-associated in AP-1-deficient cells. Moreover, although epsinR binds AP-1 via its COOH-terminal domain, its NH(2)-terminal ENTH domain can be independently recruited onto membranes, both in vivo and in vitro. Brefeldin A causes epsinR to redistribute into the cytosol, and recruitment of the ENTH domain requires GTPgammaS, indicating that membrane association is ARF dependent. In protein-lipid overlay assays, the epsinR ENTH domain binds to PtdIns(4)P, suggesting a possible mechanism for ARF-dependent recruitment onto TGN membranes. When epsinR is depleted from cells by RNAi, cathepsin D is still correctly processed intracellularly to the mature form. This indicates that although epsinR is likely to be an important component of the AP-1 network, it is not necessary for the sorting of lysosomal enzymes.

PMID:
12589059
[PubMed - indexed for MEDLINE]
PMCID:
PMC149997
Free PMC Article

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