Triadin^200–232 and triadin^200–231 peptides bind to RyR1 and exhibit a disordered secondary structure.

(A) Circular dichroism spectra averaged from four scans and corrected for the 10 mM sodium phosphate buffer are shown. Both triadin peptides (triadin^200–231 (black trace) and triadin^200–232 (grey trace); 0.03 mg/ml) show a negative peak at ∼197 nm, consistent with an intrinsically disordered structure. A positive peak at ∼190 nm and negative peaks at ∼208 and ∼223 nm (indicative of α-helical secondary structure) or a positive peak at ∼195 nm and a negative peak at ∼217 nm (indicative of β-sheet secondary structure), are absent. (B) Western blot, following streptavidin-agarose affinity chromatography, showing the association of RyR1 with biotin tagged triadin peptide. The upper half of the membrane was probed with anti-RyR1 antibody and the lower half was probed with Streptactin-HRP conjugate to identify the biotin tagged peptides. Lane 1 protein sample eluted from streptavidin-agarose incubated with RyR1 alone; Lane 2 purified RyR1 alone (control); Lane 3 biotin tagged triadin^200–231 peptide alone (control); Lanes 4 and 5 protein sample eluted from streptavidin-agarose affinity chromatography, where streptavidin-agarose was incubated with biotin tagged triadin^200–232 or triadin^200–231 peptide respectively, prior to incubation with RyR1.