MURF-1 and MURF-2 target a specific subset of myofibrillar proteins redundantly: towards understanding MURF-dependent muscle ubiquitination

J Mol Biol. 2005 Jul 22;350(4):713-22. doi: 10.1016/j.jmb.2005.05.021.


MURF-1, MURF-2 and MURF-3 are a specific class of RING finger proteins that are expressed in striated muscle tissues. MURF-1 has been suggested to act as an ubiquitin ligase, thereby controlling proteasome-dependent degradation of muscle proteins. Here, we performed yeast two-hybrid (YTH) screens of skeletal muscle cDNA libraries with MURF-1 baits to identify potential myocellular targets of MURF-1-dependent ubiquitination. This identified eight myofibrillar proteins as binding partners of MURF-1: titin, nebulin, the nebulin-related protein NRAP, troponin-I (TnI), troponin-T (TnT), myosin light chain 2 (MLC-2), myotilin and T-cap. YTH mating studies with MURF-1,2,3 baits indicated that these eight myofibrillar proteins are all targeted redundantly by both MURF-1 and MURF-2. Western blot studies on cardiac tissues from wild-type and MURF-1-deficient mice suggested that titin and nebulin were ubiquitinated at similar levels, and MLC-2 and TnI at reduced levels in MURF-1 KO mice. Mapping of the TnI and titin binding sites on MURF-1 peptide scans demonstrated their binding to motifs highly conserved between MURF-1 and MURF-2. Our data are consistent with a model in which MURF-1 and MURF-2 together target a specific set of myofibrillar proteins redundantly, most likely to control their ubiquitination-dependent degradation. Finally, our YTH screens identified the interaction of MURF-1 with 11 enzymes required for ATP/energy production in muscle including the mitochondrial ATP synthase and cytoplasmic creatine kinase. These data raise the possibility that MURF-1 may coordinately regulate the energy metabolism of mitochondrial and cytoplasmic compartments.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Mice
  • Molecular Sequence Data
  • Muscle Proteins / metabolism*
  • Muscle, Skeletal / enzymology
  • Muscle, Skeletal / metabolism*
  • Myocardium / metabolism
  • Myofibrils / metabolism*
  • Tripartite Motif Proteins
  • Ubiquitin / metabolism*
  • Ubiquitin-Protein Ligases / metabolism*


  • Muscle Proteins
  • Tripartite Motif Proteins
  • Ubiquitin
  • muscle RING finger 2 protein, mouse
  • TRIM63 protein, human
  • Trim63 protein, mouse
  • Ubiquitin-Protein Ligases