Experimentally Derived Constraints on Prion Filament Structure

Experimentally Derived Constraints on Prion Filament Structure 

We now summarize current experimentally derived constraints that models of yeast prion filaments must satisfy in addition to the basic requirement of cross-/) structure and then go on in Section VI to discuss their implications for several models that have been proposed. 

A basic structural property of protein filaments is polarity, that is, directionality. Almost all naturally occurring filaments are polar (e.g., F-actin, microtubules, TMV, and so on). The few exceptions are either bipolar, like myosin (Huxley, 1963 Squire, 1981), or nonpolar, like intermediate filaments (Herrmann and Aebi, 2004). One method of determining 

An electron micrograph of negatively stained filaments of full-length Sup35p suggests a backbone surrounded by peripheral material (Glover et al., 1997). 

Other experiments with Cys mutants and fluorescence labels and chemical cross-linking on Sup35pNM filaments (Krishnan and Lindquist, 2005) support the view that the regions from residues 21 to 38 and from 86 to 106 may also have a parallel in-register arrangement. 

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V. Experimentally Derived Constraints on Prion Filament Structure. 151... 

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