Parkin occurs in a stable, non-covalent, approximately 110-kDa complex in brain.
Mutations in the gene for parkin, a 52-kDa E3 ubiquitin ligase, are a major cause of hereditary Parkinson's disease (PD). In vitro studies have identified a large number of parkin-interacting proteins. Whether parkin exists as a monomer or as part of a stable protein complex in vivo is uncertain. Here we demonstrate that endogenous parkin occurs in a stable, non-covalent, approximately 110-kDa complex in native extracts from mouse brain, heart and skeletal muscle, while monomeric parkin is undetectable. Partial denaturation experiments indicate that this complex is at least a tetramer. Reported parkin-binding partners do not show detectable association with the parkin complex on native gels. Upon overexpression in COS1, SH-SY5Y or CHO cells, parkin accumulates predominantly as a monomer, suggesting that the interactors required for complex formation are available in limiting amounts in these cells. Importantly, PD-linked parkin mutations significantly impair parkin complex formation. These data demonstrate that parkin oligomerizes into a stable, non-covalent, heteromeric complex in vivo, and suggest that parkin may have as yet unidentified stable binding partners.
Van Humbeeck
Cindy
C
Department of Neurosciences, Division of Experimental Neurology, University of Leuven, Leuven, Belgium.
Waelkens
Etienne
E
Corti
Olga
O
Brice
Alexis
A
Vandenberghe
Wim
W
D000818:Animals; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry / Q000502:physiology*; D016466:CHO Cells; D019556:COS Cells; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D044767:Ubiquitin-Protein Ligases / Q000032:analysis* / Q000096:biosynthesis* / Q000235:genetics
D044767:Ubiquitin-Protein Ligases; C111567:parkin protein