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Published June 2012 | Published + Supplemental Material
Journal Article Open

Protein Interaction Profiling of the p97 Adaptor UBXD1 Points to a Role for the Complex in Modulating ERGIC-53 Trafficking


UBXD1 is a member of the poorly understood subfamily of p97 adaptors that do not harbor a ubiquitin association domain or bind ubiquitin-modified proteins. Of clinical importance, p97 mutants found in familial neurodegenerative conditions Inclusion Body Myopathy Paget's disease of the bone and/or Frontotemporal Dementia and Amyotrophic Lateral Sclerosis are defective at interacting with UBXD1, indicating that functions regulated by a p97-UBXD1 complex are altered in these diseases. We have performed liquid chromatography-mass spectrometric analysis of UBXD1-interacting proteins to identify pathways in which UBXD1 functions. UBXD1 displays prominent association with ERGIC-53, a hexameric type I integral membrane protein that functions in protein trafficking. The UBXD1-ERGIC-53 interaction requires the N-terminal 10 residues of UBXD1 and the C-terminal cytoplasmic 12 amino acid tail of ERGIC-53. Use of p97 and E1 enzyme inhibitors indicate that complex formation between UBXD1 and ERGIC-53 requires the ATPase activity of p97, but not ubiquitin modification. We also performed SILAC-based quantitative proteomic profiling to identify ERGIC-53 interacting proteins. This analysis identified known (e.g. COPI subunits) and novel (Rab3GAP1/2 complex involved in the fusion of vesicles at the cell membrane) interactions that are also mediated through the C terminus of the protein. Immunoprecipitation and Western blotting analysis confirmed the proteomic interaction data and it also revealed that an UBXD1-Rab3GAP association requires the ERGIC-53 binding domain of UBXD1. Localization studies indicate that UBXD1 modules the sub-cellular trafficking of ERGIC-53, including promoting movement to the cell membrane. We propose that p97-UBXD1 modulates the trafficking of ERGIC-53-containing vesicles by controlling the interaction of transport factors with the cytoplasmic tail of ERGIC-53.

Additional Information

© 2012 by The American Society for Biochemistry and Molecular Biology, Inc. Received December 12, 2011. Published, MCP Papers in Press, February 14, 2012. DSH thanks his Department and Institute Chairs for permission to perform summer work at Caltech. DSH acknowledges support from the Fels Institute for Cancer Research and Molecular Biology and the Temple University Faculty Senate Seed funds. JEL was supported by the Ruth L. Kirschstein NRSA fellowship CA138126 whereas WBD was supported by the Ruth L. Kirschstein NRSA fellowship GM088975. The Proteome Exploration Lab was supported by the Beckman Institute at Caltech and an award from the Gordon and Betty Moore Foundation. RJD is an Investigator of the Howard Hughes Medical Institute and this work was supported in part by HHMI.

Attached Files

Published - Haines2012p19032Mol_Cell_Proteomics.pdf

Supplemental Material - mcp.M111.016444-1.pdf

Supplemental Material - mcp.M111.016444-2.txt

Supplemental Material - mcp.M111.016444-3.txt

Supplemental Material - mcp.M111.016444-4.txt

Supplemental Material - mcp.M111.016444-5.txt


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August 19, 2023
October 18, 2023