Parkin occurs in a stable, non-covalent, approximately 110-kDa complex in brain

Authors:
Van Humbeeck C, Waelkens E, Corti O, Brice A, Vandenberghe W
In:
Source: Eur J Neurosci
Publication Date: (2008)
Issue: 27(2): 284-93
Research Area:
Cancer Research/Cell Biology
Neurobiology
Cells used in publication:
SH-SY5Y
Species: human
Tissue Origin: brain
Platform:
Nucleofectorâ„¢ I/II/2b
Abstract
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.