Figure 1. Mass Spectra of the τ and γ Subunits in Isolation.

(A) Mass spectrum of τ in 0.1 M NH₄OAc at pH 7.6 and 1 mM dithiothreitol. The major charge state series corresponds to a tetrameric form of τ. Series of τ in monomeric, dimeric, and trimeric forms are also observed as the minor charge state series.

(B) Mass spectrum of γ in 0.1 M NH₄OAc at pH 6.9. Well resolved charge states indicate that γ forms a well defined tetramer.

(C) Mass spectrum of all four oligomeric species of γ in 1 M NH₄OAc at pH 6.9. See also Table S1.