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. Author manuscript; available in PMC: 2009 Oct 1.
Published in final edited form as: Trends Neurosci. 2008 Sep 6;31(10):521–528. doi: 10.1016/j.tins.2008.07.004

Figure 1. Possible cellular sequelae of expanded polyQ protein misfolding.

Figure 1

PolyQ proteins, when expanded, are prone to misfold. HSF-1 can trigger the expression of certain chaperones, including Hsp70 and Hsp40, which help refold misfolded polyQ proteins. When misfolded polyQ monomers form oligomers, chaperones can help to dissociate them. Misfolded monomers can also form complexes with other proteins. These aberrant heteroprotein complexes may cause the affected proteins to adopt novel functions or alter their normal functions. Oligomers may also interact with cellular proteins to cause similar alterations in function, though currently there is no direct experimental evidence. Some protein quality control components, such as the TRiC chaperonin complex, may reduce the toxicity of oligomers by changing their size and conformation. Based on current evidence, we suggest misfolded, polyQ-expanded monomers and resultant oligomers display reactive, accessible polypeptide surfaces that cause neuronal dysfunction and ultimately cell death.