Fig. 4.

Differential recruitment of Hsp90 contributes to cardiac 19S complex heterogeneity. A, The molecular identity of 19S-associated Hsp90 was confirmed with LC-MS/MS following nondenaturing native PAGE. The spectrum for Hsp90 peptide ₂₉₂NPDDITQEEYGEFYK₃₀₆ was shown. B, Quantitative immunoblotting assays with Hsp90 specific antibodies demonstrated that Hsp90 was unique to subpopulation 19S I. The relative contents of 19S subunits Rpt2, Rpt4, Rpn2 and Rpn7 were also probed as loading controls. C, Two-dimensional native PAGE and SDS-PAGE was performed for 19S I, confirming the interaction of Hsp90 with 19S I under a native, nondenaturing state.