A protein interaction network for Ecm29 links the 26 S proteasome to molecular motors and endosomal components

J Biol Chem. 2010 Oct 8;285(41):31616-33. doi: 10.1074/jbc.M110.154120. Epub 2010 Aug 3.


Ecm29 is a 200-kDa HEAT repeat protein that binds the 26 S proteasome. Genome-wide two-hybrid screens and mass spectrometry have identified molecular motors, endosomal components, and ubiquitin-proteasome factors as Ecm29-interacting proteins. The C-terminal half of human Ecm29 binds myosins and kinesins; its N-terminal region binds the endocytic proteins, Vps11, Rab11-FIP4, and rabaptin. Whereas full-length FLAG-Ecm29, its C-terminal half, and a small central fragment of Ecm29 remain bound to glycerol-gradient-separated 26 S proteasomes, the N-terminal half of Ecm29 does not. Confocal microscopy showed that Ecm-26 S proteasomes are present on flotillin-positive endosomes, but they are virtually absent from caveolin- and clathrin-decorated endosomes. Expression of the small central fragment of Ecm29 markedly reduces proteasome association with flotillin-positive endosomes. Identification of regions within Ecm29 capable of binding molecular motors, endosomal proteins, and the 26 S proteasome supports the hypothesis that Ecm29 serves as an adaptor for coupling 26 S proteasomes to specific cellular compartments.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Endosomes / genetics
  • Endosomes / metabolism*
  • HeLa Cells
  • Humans
  • Mice
  • Molecular Motor Proteins / genetics
  • Molecular Motor Proteins / metabolism*
  • Proteasome Endopeptidase Complex / genetics
  • Proteasome Endopeptidase Complex / metabolism*
  • Vesicular Transport Proteins / genetics
  • Vesicular Transport Proteins / metabolism
  • rab GTP-Binding Proteins / genetics
  • rab GTP-Binding Proteins / metabolism


  • ECPAS protein, human
  • Molecular Motor Proteins
  • VPS11 protein, human
  • Vesicular Transport Proteins
  • Proteasome Endopeptidase Complex
  • ATP dependent 26S protease
  • rab11 protein
  • rab GTP-Binding Proteins